<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2023 Workiva-->
<!--r:0d753121-8905-47cf-9c1b-b2fde7ad11ce,g:ff7ff55b-7d0b-4a0b-afc5-39e8fe33ba9c-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://ucbi.com/role/Cover" xlink:type="simple" xlink:href="ucbi-20230331.xsd#Cover"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/Cover" xlink:type="extended" id="ia0ebefbb45a24fb4ad836aeca6740ed5_Cover">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityListingsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_6dfa2f44-be80-4c59-b70c-8b7399ccc9a8" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_DocumentType_6dfa2f44-be80-4c59-b70c-8b7399ccc9a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_2a6dfa58-0bbc-4f0a-bd90-607764a0e46c" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_DocumentQuarterlyReport_2a6dfa58-0bbc-4f0a-bd90-607764a0e46c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_9658a48b-dba4-4894-84c2-9e77ccce801a" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_DocumentPeriodEndDate_9658a48b-dba4-4894-84c2-9e77ccce801a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_a104eaea-4363-4d92-a9f8-44f61eb9ed24" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_DocumentTransitionReport_a104eaea-4363-4d92-a9f8-44f61eb9ed24" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_bb9013f8-7a89-426a-8a36-911e90a045ac" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityFileNumber_bb9013f8-7a89-426a-8a36-911e90a045ac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_44b212fa-6ab8-4d45-8c8b-f418a3c5a197" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityRegistrantName_44b212fa-6ab8-4d45-8c8b-f418a3c5a197" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_f78dcf75-e5fe-4ac0-8b6c-d622524ca6b5" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityIncorporationStateCountryCode_f78dcf75-e5fe-4ac0-8b6c-d622524ca6b5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_13e2b045-ceca-480a-a007-a33212078e65" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityTaxIdentificationNumber_13e2b045-ceca-480a-a007-a33212078e65" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_c90e88c0-607b-497e-9f75-35362d4edd3c" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityAddressAddressLine1_c90e88c0-607b-497e-9f75-35362d4edd3c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_25348bb2-8e99-4fb2-a1b4-89d520ae3c5a" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityAddressCityOrTown_25348bb2-8e99-4fb2-a1b4-89d520ae3c5a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_0f005d7c-8685-4872-be80-9072149ed037" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityAddressStateOrProvince_0f005d7c-8685-4872-be80-9072149ed037" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_9b27b392-d73c-4fdb-aa18-7c435539d3eb" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityAddressPostalZipCode_9b27b392-d73c-4fdb-aa18-7c435539d3eb" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_2b740b53-ada1-4ded-b312-e37765080655" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_CityAreaCode_2b740b53-ada1-4ded-b312-e37765080655" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_39736eb2-bc40-47c8-9234-c00e14ab0025" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_LocalPhoneNumber_39736eb2-bc40-47c8-9234-c00e14ab0025" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_3ddc2dee-63c2-407f-bdcf-c17a75aca39c" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_Security12bTitle_3ddc2dee-63c2-407f-bdcf-c17a75aca39c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_44a86277-257b-4fd7-b461-063b3367e0ff" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_TradingSymbol_44a86277-257b-4fd7-b461-063b3367e0ff" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_725de423-36dc-4b99-8181-879ca1d53fe0" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_SecurityExchangeName_725de423-36dc-4b99-8181-879ca1d53fe0" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_b31a2480-22ff-4275-b07c-4adea05b054a" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityCurrentReportingStatus_b31a2480-22ff-4275-b07c-4adea05b054a" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_701a05c3-e8eb-49ee-9ce4-20518672637c" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityInteractiveDataCurrent_701a05c3-e8eb-49ee-9ce4-20518672637c" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_6c9e260a-9055-48a5-b790-266387a242e1" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityFilerCategory_6c9e260a-9055-48a5-b790-266387a242e1" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_57175d95-09c6-4ebf-901a-ead0519079e3" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntitySmallBusiness_57175d95-09c6-4ebf-901a-ead0519079e3" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_c53e9391-7c66-4814-bc63-54bb8af42711" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityEmergingGrowthCompany_c53e9391-7c66-4814-bc63-54bb8af42711" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_7d095eb1-fadf-4e4d-a59c-773ab8c6a2c8" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityShellCompany_7d095eb1-fadf-4e4d-a59c-773ab8c6a2c8" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_4ae31a26-7ba4-4d13-82c4-939c5823643c" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_4ae31a26-7ba4-4d13-82c4-939c5823643c" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_9c5bb657-0e6d-4d95-b208-37c08d2e4a9e" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityCentralIndexKey_9c5bb657-0e6d-4d95-b208-37c08d2e4a9e" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_b21c370b-7f86-4d75-a5a6-de0899aef8ff" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_CurrentFiscalYearEndDate_b21c370b-7f86-4d75-a5a6-de0899aef8ff" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_6b06ca86-30cb-43dc-b8a2-e5ddd8ee4305" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_DocumentFiscalYearFocus_6b06ca86-30cb-43dc-b8a2-e5ddd8ee4305" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_e7a5e63b-5a2e-4689-b0bc-2dd8ae945116" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_DocumentFiscalPeriodFocus_e7a5e63b-5a2e-4689-b0bc-2dd8ae945116" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_11f684b9-dbd4-48e4-a411-b6de60b6f87b" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_AmendmentFlag_11f684b9-dbd4-48e4-a411-b6de60b6f87b" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityListingsTable_ea5cc7dd-72cf-4808-b65f-c8f785b83512" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityListingsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityListingsLineItems_dd68863c-b9d5-4d2e-b426-8b3015e198f1" xlink:to="loc_dei_EntityListingsTable_ea5cc7dd-72cf-4808-b65f-c8f785b83512" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_4191ac2b-1bb7-4814-906c-65b9fbd3012d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntityListingsTable_ea5cc7dd-72cf-4808-b65f-c8f785b83512" xlink:to="loc_us-gaap_StatementClassOfStockAxis_4191ac2b-1bb7-4814-906c-65b9fbd3012d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_4191ac2b-1bb7-4814-906c-65b9fbd3012d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4191ac2b-1bb7-4814-906c-65b9fbd3012d" xlink:to="loc_us-gaap_ClassOfStockDomain_4191ac2b-1bb7-4814-906c-65b9fbd3012d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5504a0db-0417-4017-a99e-624b219f8887" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4191ac2b-1bb7-4814-906c-65b9fbd3012d" xlink:to="loc_us-gaap_ClassOfStockDomain_5504a0db-0417-4017-a99e-624b219f8887" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_ac505336-e634-4453-a79c-56093848c289" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5504a0db-0417-4017-a99e-624b219f8887" xlink:to="loc_us-gaap_CommonStockMember_ac505336-e634-4453-a79c-56093848c289" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DepositaryShareOnUCBISeriesINonCumulativePreferredStockMember_37feb1ab-677b-4ef6-a8cb-7f9a1fe9742d" xlink:href="ucbi-20230331.xsd#ucbi_DepositaryShareOnUCBISeriesINonCumulativePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_5504a0db-0417-4017-a99e-624b219f8887" xlink:to="loc_ucbi_DepositaryShareOnUCBISeriesINonCumulativePreferredStockMember_37feb1ab-677b-4ef6-a8cb-7f9a1fe9742d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/ConsolidatedStatementsofIncomeUnaudited" xlink:type="simple" xlink:href="ucbi-20230331.xsd#ConsolidatedStatementsofIncomeUnaudited"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/ConsolidatedStatementsofIncomeUnaudited" xlink:type="extended" id="iaccd1f0a816046f7b96efd26842ac328_ConsolidatedStatementsofIncomeUnaudited">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDividendIncomeOperatingAbstract_a550c037-7188-4ad0-9972-0e2588bdc296" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestAndDividendIncomeOperatingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_InterestAndDividendIncomeOperatingAbstract_a550c037-7188-4ad0-9972-0e2588bdc296" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndFeeIncomeLoansAndLeases_59d36f69-c86a-4de0-b72f-477051181abb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestAndFeeIncomeLoansAndLeases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperatingAbstract_a550c037-7188-4ad0-9972-0e2588bdc296" xlink:to="loc_us-gaap_InterestAndFeeIncomeLoansAndLeases_59d36f69-c86a-4de0-b72f-477051181abb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDividendIncomeSecurities_cdca086f-e3b5-4bc9-9764-3e8a94127279" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestAndDividendIncomeSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperatingAbstract_a550c037-7188-4ad0-9972-0e2588bdc296" xlink:to="loc_us-gaap_InterestAndDividendIncomeSecurities_cdca086f-e3b5-4bc9-9764-3e8a94127279" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FederalFundsSoldCommercialPaperAndDepositsInBanks_700121b1-03a2-4ae8-9527-0f4adae92fc0" xlink:href="ucbi-20230331.xsd#ucbi_FederalFundsSoldCommercialPaperAndDepositsInBanks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperatingAbstract_a550c037-7188-4ad0-9972-0e2588bdc296" xlink:to="loc_ucbi_FederalFundsSoldCommercialPaperAndDepositsInBanks_700121b1-03a2-4ae8-9527-0f4adae92fc0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDividendIncomeOperating_6ac5862c-a4aa-4a02-9692-98e07493dd09" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestAndDividendIncomeOperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestAndDividendIncomeOperatingAbstract_a550c037-7188-4ad0-9972-0e2588bdc296" xlink:to="loc_us-gaap_InterestAndDividendIncomeOperating_6ac5862c-a4aa-4a02-9692-98e07493dd09" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseAbstract_8da616b7-0dbd-448d-99e4-6fa4faa9487e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_InterestExpenseAbstract_8da616b7-0dbd-448d-99e4-6fa4faa9487e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDeposits_da42df44-17cc-491e-ae83-9a8ff28eb485" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseAbstract_8da616b7-0dbd-448d-99e4-6fa4faa9487e" xlink:to="loc_us-gaap_InterestExpenseDeposits_da42df44-17cc-491e-ae83-9a8ff28eb485" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOtherShortTermBorrowings_3aa788cc-947b-4e7a-ab1e-4c6ba535ae42" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseOtherShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseAbstract_8da616b7-0dbd-448d-99e4-6fa4faa9487e" xlink:to="loc_us-gaap_InterestExpenseOtherShortTermBorrowings_3aa788cc-947b-4e7a-ab1e-4c6ba535ae42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseFederalHomeLoanBankAndFederalReserveBankAdvancesShortTerm_a6248f79-4213-4764-b01c-a9652305e7f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseFederalHomeLoanBankAndFederalReserveBankAdvancesShortTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseAbstract_8da616b7-0dbd-448d-99e4-6fa4faa9487e" xlink:to="loc_us-gaap_InterestExpenseFederalHomeLoanBankAndFederalReserveBankAdvancesShortTerm_a6248f79-4213-4764-b01c-a9652305e7f3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseLongTermDebt_aeafc1b1-a797-4ecf-8c56-72207fe83634" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseAbstract_8da616b7-0dbd-448d-99e4-6fa4faa9487e" xlink:to="loc_us-gaap_InterestExpenseLongTermDebt_aeafc1b1-a797-4ecf-8c56-72207fe83634" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_4f6f8a90-2c76-4148-9b37-e6a65728ee48" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseAbstract_8da616b7-0dbd-448d-99e4-6fa4faa9487e" xlink:to="loc_us-gaap_InterestExpense_4f6f8a90-2c76-4148-9b37-e6a65728ee48" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_052ed535-3872-4ac1-92de-16fd9b63ea92" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_052ed535-3872-4ac1-92de-16fd9b63ea92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_6bad9fbf-a978-4d65-88fe-8db4ac761c61" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForLoanLeaseAndOtherLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_6bad9fbf-a978-4d65-88fe-8db4ac761c61" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_7ab33543-33bb-4cdf-b0a3-f4feaf26c90d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss_7ab33543-33bb-4cdf-b0a3-f4feaf26c90d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoninterestIncomeAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncomeOther_6d4c3276-980c-4baf-a197-ee5cc3e3efe7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoninterestIncomeOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:to="loc_us-gaap_NoninterestIncomeOther_6d4c3276-980c-4baf-a197-ee5cc3e3efe7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentBankingAdvisoryBrokerageAndUnderwritingFeesAndCommissions_fa19dd32-038c-4f46-857e-15e184381fc2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentBankingAdvisoryBrokerageAndUnderwritingFeesAndCommissions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:to="loc_us-gaap_InvestmentBankingAdvisoryBrokerageAndUnderwritingFeesAndCommissions_fa19dd32-038c-4f46-857e-15e184381fc2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSalesOfLoansNet_aac2164c-1770-4520-aefc-1d779953b0c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSalesOfLoansNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:to="loc_us-gaap_GainLossOnSalesOfLoansNet_aac2164c-1770-4520-aefc-1d779953b0c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_OtherLendingAndLoanServicingFees_0a970b7f-f6e0-4cc0-b5b4-c95b40835283" xlink:href="ucbi-20230331.xsd#ucbi_OtherLendingAndLoanServicingFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:to="loc_ucbi_OtherLendingAndLoanServicingFees_0a970b7f-f6e0-4cc0-b5b4-c95b40835283" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_fbefadad-09db-4ae3-aa82-a151ee5bf93a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_fbefadad-09db-4ae3-aa82-a151ee5bf93a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncomeOtherOperatingIncome_2b4cb12d-1b0b-4ade-93f6-b78558872d94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoninterestIncomeOtherOperatingIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:to="loc_us-gaap_NoninterestIncomeOtherOperatingIncome_2b4cb12d-1b0b-4ade-93f6-b78558872d94" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestIncome_5a22105e-6ee8-4b9b-8023-7ab64c68347a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoninterestIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoninterestIncomeAbstract_80d072d1-5e05-474e-8800-4129d7f3ce0b" xlink:to="loc_us-gaap_NoninterestIncome_5a22105e-6ee8-4b9b-8023-7ab64c68347a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_d4f9634d-628b-4b4a-95da-1562fbf370ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_Revenues_d4f9634d-628b-4b4a-95da-1562fbf370ec" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_0637d4a9-031c-40e2-a98f-1f761b8856dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_LaborAndRelatedExpense_0637d4a9-031c-40e2-a98f-1f761b8856dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommunicationsAndInformationTechnology_c03b399d-ecc1-43f6-8f87-4616f1609d31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommunicationsAndInformationTechnology"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_CommunicationsAndInformationTechnology_c03b399d-ecc1-43f6-8f87-4616f1609d31" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OccupancyNet_b39a1d69-c6d5-4ee3-b8a7-5fe8d4c0591d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OccupancyNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_OccupancyNet_b39a1d69-c6d5-4ee3-b8a7-5fe8d4c0591d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketingAndAdvertisingExpense_17ba757b-edab-4efb-86cf-26c66655bb45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketingAndAdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_MarketingAndAdvertisingExpense_17ba757b-edab-4efb-86cf-26c66655bb45" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SuppliesAndPostageExpense_1ffd434e-1497-4a76-89dd-5efca6f3be00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SuppliesAndPostageExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_SuppliesAndPostageExpense_1ffd434e-1497-4a76-89dd-5efca6f3be00" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfessionalFees_45edc0ec-8074-4b1a-af2a-bf3e64f7bdc1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfessionalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_ProfessionalFees_45edc0ec-8074-4b1a-af2a-bf3e64f7bdc1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanPortfolioExpense_3f7af0fe-8b80-4658-84b7-0687b4d8196e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoanPortfolioExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_LoanPortfolioExpense_3f7af0fe-8b80-4658-84b7-0687b4d8196e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_NoninterestExpenseOutsideServicesElectronicBanking_a24a4656-1016-4857-b25e-d6e85cfbb61f" xlink:href="ucbi-20230331.xsd#ucbi_NoninterestExpenseOutsideServicesElectronicBanking"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_ucbi_NoninterestExpenseOutsideServicesElectronicBanking_a24a4656-1016-4857-b25e-d6e85cfbb61f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalDepositInsuranceCorporationPremiumExpense_b2a5667d-8201-4d81-8638-93d38260a52f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FederalDepositInsuranceCorporationPremiumExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_FederalDepositInsuranceCorporationPremiumExpense_b2a5667d-8201-4d81-8638-93d38260a52f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_dc348ee8-d41d-446b-9481-1c327d9b9d25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_dc348ee8-d41d-446b-9481-1c327d9b9d25" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_64dc6186-a002-4d1a-ae55-7daded7c2add" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_64dc6186-a002-4d1a-ae55-7daded7c2add" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoninterestExpense_b350d7ef-a439-4f70-bdba-d3d3b99f0229" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoninterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_OtherNoninterestExpense_b350d7ef-a439-4f70-bdba-d3d3b99f0229" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoninterestExpense_4d704ae6-7d2e-42d0-a8c1-880319140a26" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoninterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_886c51e8-f6c5-435e-a64a-aee6c80a5d4b" xlink:to="loc_us-gaap_NoninterestExpense_4d704ae6-7d2e-42d0-a8c1-880319140a26" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_7cfded45-23c2-443e-80c7-c1cf4d50264f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_7cfded45-23c2-443e-80c7-c1cf4d50264f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_9d295b5a-5413-46a0-8e00-b9a44548c914" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_9d295b5a-5413-46a0-8e00-b9a44548c914" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_ead45a79-fd58-4972-bef6-76a37462ccdc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_NetIncomeLoss_ead45a79-fd58-4972-bef6-76a37462ccdc" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_b4f2e476-a209-4428-a05d-a2813fca5366" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_b4f2e476-a209-4428-a05d-a2813fca5366" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_b7b2bc10-21dd-4d07-81e7-aa12b9ed39ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_b7b2bc10-21dd-4d07-81e7-aa12b9ed39ca" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_190813c5-fa88-4023-b223-319992de9b0d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_EarningsPerShareAbstract_190813c5-fa88-4023-b223-319992de9b0d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_49467686-327e-401b-9028-045e58135851" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_190813c5-fa88-4023-b223-319992de9b0d" xlink:to="loc_us-gaap_EarningsPerShareBasic_49467686-327e-401b-9028-045e58135851" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_c58afd46-6ef8-4cc3-ac3e-691b2e9025f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_190813c5-fa88-4023-b223-319992de9b0d" xlink:to="loc_us-gaap_EarningsPerShareDiluted_c58afd46-6ef8-4cc3-ac3e-691b2e9025f6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_5afe15b4-2614-4142-bd5d-13017d9aaa00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_5afe15b4-2614-4142-bd5d-13017d9aaa00" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_c929ef10-3d2b-45ce-b395-c1815d2a385b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_5afe15b4-2614-4142-bd5d-13017d9aaa00" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_c929ef10-3d2b-45ce-b395-c1815d2a385b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_75226aec-35bd-4f23-90c0-5c7d8302453b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_5afe15b4-2614-4142-bd5d-13017d9aaa00" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_75226aec-35bd-4f23-90c0-5c7d8302453b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_762b362a-72f6-455e-8b9e-343d24efa9c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_33472424-ec92-47f5-87a9-b2e0eb2d4969" xlink:to="loc_us-gaap_StatementTable_762b362a-72f6-455e-8b9e-343d24efa9c0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_2d368d8f-0965-4c17-833f-0d80dbf61353" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_762b362a-72f6-455e-8b9e-343d24efa9c0" xlink:to="loc_srt_ProductOrServiceAxis_2d368d8f-0965-4c17-833f-0d80dbf61353" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_2d368d8f-0965-4c17-833f-0d80dbf61353_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_2d368d8f-0965-4c17-833f-0d80dbf61353" xlink:to="loc_srt_ProductsAndServicesDomain_2d368d8f-0965-4c17-833f-0d80dbf61353_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5a23a93d-2586-4864-8bc5-b533393a5c2c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_2d368d8f-0965-4c17-833f-0d80dbf61353" xlink:to="loc_srt_ProductsAndServicesDomain_5a23a93d-2586-4864-8bc5-b533393a5c2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositAccountMember_5cdbeed4-8343-4d47-9951-a1bd8599301f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepositAccountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_5a23a93d-2586-4864-8bc5-b533393a5c2c" xlink:to="loc_us-gaap_DepositAccountMember_5cdbeed4-8343-4d47-9951-a1bd8599301f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgageBankingMember_f11ba2ba-0578-45cd-add8-b4801fc8720e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MortgageBankingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_5a23a93d-2586-4864-8bc5-b533393a5c2c" xlink:to="loc_us-gaap_MortgageBankingMember_f11ba2ba-0578-45cd-add8-b4801fc8720e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/ConsolidatedStatementofChangesinShareholdersEquityUnaudited" xlink:type="simple" xlink:href="ucbi-20230331.xsd#ConsolidatedStatementofChangesinShareholdersEquityUnaudited"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/ConsolidatedStatementofChangesinShareholdersEquityUnaudited" xlink:type="extended" id="i21cfc694c9c44153b9d32fb4d4618114_ConsolidatedStatementofChangesinShareholdersEquityUnaudited">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_ceda59e7-7579-4509-88bf-63b0d96f2869" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ceda59e7-7579-4509-88bf-63b0d96f2869" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_2373c67f-1897-429a-ac26-7ff2dbf91fe6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_2373c67f-1897-429a-ac26-7ff2dbf91fe6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_08ada604-419b-469d-8f9a-2225db957af7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_StockholdersEquity_08ada604-419b-469d-8f9a-2225db957af7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_0bbcbb2f-e596-4751-a626-c423ddc7e2c5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_NetIncomeLoss_0bbcbb2f-e596-4751-a626-c423ddc7e2c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_f66141ba-be08-470f-b854-b8b680ea5bb4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_f66141ba-be08-470f-b854-b8b680ea5bb4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_6cdd9bba-6a5a-4e86-9582-04df347808a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_6cdd9bba-6a5a-4e86-9582-04df347808a4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_8cd54650-8416-4e17-a1e8-672f4b440169" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_8cd54650-8416-4e17-a1e8-672f4b440169" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStock_60bc61d2-1790-45b9-985f-38c3933a6ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_DividendsPreferredStock_60bc61d2-1790-45b9-985f-38c3933a6ca5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_2374d01f-ff9f-4ff0-aefe-c5db585714c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_DividendsCommonStockCash_2374d01f-ff9f-4ff0-aefe-c5db585714c2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_aef904ae-8327-494f-bbf0-0a4b817e8a35" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_aef904ae-8327-494f-bbf0-0a4b817e8a35" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_08331042-f6b9-48df-988b-595a5d8fae57" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_08331042-f6b9-48df-988b-595a5d8fae57" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_StockIssuedDuringPeriodSharesDividendReinvestmentPlanEmployeeBenefitPlansAndDeferredCompensation_d4112efa-f920-467a-87e1-1613be96a307" xlink:href="ucbi-20230331.xsd#ucbi_StockIssuedDuringPeriodSharesDividendReinvestmentPlanEmployeeBenefitPlansAndDeferredCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_ucbi_StockIssuedDuringPeriodSharesDividendReinvestmentPlanEmployeeBenefitPlansAndDeferredCompensation_d4112efa-f920-467a-87e1-1613be96a307" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_StockIssuedDuringPeriodValueDividendReinvestmentPlanEmployeeBenefitPlansAndDeferredCompensation_0f60b2be-bb97-4c1f-b220-9789fdbb34cb" xlink:href="ucbi-20230331.xsd#ucbi_StockIssuedDuringPeriodValueDividendReinvestmentPlanEmployeeBenefitPlansAndDeferredCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_27f5329e-a5b1-46ed-9f01-35e25b490a41" xlink:to="loc_ucbi_StockIssuedDuringPeriodValueDividendReinvestmentPlanEmployeeBenefitPlansAndDeferredCompensation_0f60b2be-bb97-4c1f-b220-9789fdbb34cb" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_2047996b-7b38-423f-83e5-6532fc6c863e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_9893daad-4ad9-4e3b-8758-30ec451f445e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_1ca41d02-82cb-4203-804c-f4f60463ab54" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_ceda59e7-7579-4509-88bf-63b0d96f2869" xlink:to="loc_us-gaap_StatementTable_1ca41d02-82cb-4203-804c-f4f60463ab54" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_55affdb0-e922-4f49-b5e7-a3e0e31743b3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1ca41d02-82cb-4203-804c-f4f60463ab54" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_55affdb0-e922-4f49-b5e7-a3e0e31743b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_55affdb0-e922-4f49-b5e7-a3e0e31743b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_55affdb0-e922-4f49-b5e7-a3e0e31743b3" xlink:to="loc_us-gaap_EquityComponentDomain_55affdb0-e922-4f49-b5e7-a3e0e31743b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_df9e875d-cc59-4e3f-a4fb-1689adbe5cd4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_55affdb0-e922-4f49-b5e7-a3e0e31743b3" xlink:to="loc_us-gaap_EquityComponentDomain_df9e875d-cc59-4e3f-a4fb-1689adbe5cd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_69d370c7-7347-4cd5-97cf-bff430caf42e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_df9e875d-cc59-4e3f-a4fb-1689adbe5cd4" xlink:to="loc_us-gaap_CommonStockMember_69d370c7-7347-4cd5-97cf-bff430caf42e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_5379015e-4635-4bca-aa98-e9c2a282f7c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_df9e875d-cc59-4e3f-a4fb-1689adbe5cd4" xlink:to="loc_us-gaap_PreferredStockMember_5379015e-4635-4bca-aa98-e9c2a282f7c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommonStockIssuableMember_95e33ae7-a476-4cd3-96b8-7b1147a1d0a6" xlink:href="ucbi-20230331.xsd#ucbi_CommonStockIssuableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_df9e875d-cc59-4e3f-a4fb-1689adbe5cd4" xlink:to="loc_ucbi_CommonStockIssuableMember_95e33ae7-a476-4cd3-96b8-7b1147a1d0a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_9deaf9d3-3ef3-4db0-a1e1-971f53a61113" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_df9e875d-cc59-4e3f-a4fb-1689adbe5cd4" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_9deaf9d3-3ef3-4db0-a1e1-971f53a61113" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_dda4664a-481d-41c2-8579-76e3f0eb56f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_df9e875d-cc59-4e3f-a4fb-1689adbe5cd4" xlink:to="loc_us-gaap_RetainedEarningsMember_dda4664a-481d-41c2-8579-76e3f0eb56f4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_5aa2c9e0-214e-4484-b451-08c75e40fb01" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_df9e875d-cc59-4e3f-a4fb-1689adbe5cd4" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_5aa2c9e0-214e-4484-b451-08c75e40fb01" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AcquisitionsNarrativeDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AcquisitionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AcquisitionsNarrativeDetails" xlink:type="extended" id="ia93c63700f5a4c77b8690deb36c39f12_AcquisitionsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_12811f48-85d0-4f9b-b2c6-591acb518f1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_NumberOfBranches_3b342cca-48ad-42ea-b7e7-9f77c6c06b5d" xlink:href="ucbi-20230331.xsd#ucbi_NumberOfBranches"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12811f48-85d0-4f9b-b2c6-591acb518f1f" xlink:to="loc_ucbi_NumberOfBranches_3b342cca-48ad-42ea-b7e7-9f77c6c06b5d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_3f73ff4a-ce3f-4b20-a895-b426c079113d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12811f48-85d0-4f9b-b2c6-591acb518f1f" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_3f73ff4a-ce3f-4b20-a895-b426c079113d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_6162e3a7-e53e-40a2-a62c-3fff5eb85079" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12811f48-85d0-4f9b-b2c6-591acb518f1f" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_6162e3a7-e53e-40a2-a62c-3fff5eb85079" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_83f0ef90-24bf-4c84-a6b2-592935968bd6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12811f48-85d0-4f9b-b2c6-591acb518f1f" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_83f0ef90-24bf-4c84-a6b2-592935968bd6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4ffb6174-3384-4d6f-9b74-c9ac66bf4cc2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_12811f48-85d0-4f9b-b2c6-591acb518f1f" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4ffb6174-3384-4d6f-9b74-c9ac66bf4cc2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_636c0e54-6e15-416a-85a9-f3e5860e7159" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4ffb6174-3384-4d6f-9b74-c9ac66bf4cc2" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_636c0e54-6e15-416a-85a9-f3e5860e7159" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_636c0e54-6e15-416a-85a9-f3e5860e7159_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_636c0e54-6e15-416a-85a9-f3e5860e7159" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_636c0e54-6e15-416a-85a9-f3e5860e7159_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_418f3de7-6955-4e24-8521-caf696ec5dea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_636c0e54-6e15-416a-85a9-f3e5860e7159" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_418f3de7-6955-4e24-8521-caf696ec5dea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ProgressBankTrustMember_e7f08721-6266-4d26-8e1c-9ab0c4c3ef5e" xlink:href="ucbi-20230331.xsd#ucbi_ProgressBankTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_418f3de7-6955-4e24-8521-caf696ec5dea" xlink:to="loc_ucbi_ProgressBankTrustMember_e7f08721-6266-4d26-8e1c-9ab0c4c3ef5e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentAxis_ca405f98-3e26-4c3e-8242-914a4529b591" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonrecurringAdjustmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4ffb6174-3384-4d6f-9b74-c9ac66bf4cc2" xlink:to="loc_us-gaap_NonrecurringAdjustmentAxis_ca405f98-3e26-4c3e-8242-914a4529b591" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_ca405f98-3e26-4c3e-8242-914a4529b591_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_ca405f98-3e26-4c3e-8242-914a4529b591" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_ca405f98-3e26-4c3e-8242-914a4529b591_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_792e0b7f-5eed-4271-8f93-e88ac01d9a06" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_ca405f98-3e26-4c3e-8242-914a4529b591" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_792e0b7f-5eed-4271-8f93-e88ac01d9a06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquisitionRelatedCostsMember_58bab9b7-4896-4da1-a0aa-15e8e9d97a08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquisitionRelatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_792e0b7f-5eed-4271-8f93-e88ac01d9a06" xlink:to="loc_us-gaap_AcquisitionRelatedCostsMember_58bab9b7-4896-4da1-a0aa-15e8e9d97a08" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2f7b20c3-7b94-4149-b740-3fb94102b6a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_4ffb6174-3384-4d6f-9b74-c9ac66bf4cc2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2f7b20c3-7b94-4149-b740-3fb94102b6a6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2f7b20c3-7b94-4149-b740-3fb94102b6a6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2f7b20c3-7b94-4149-b740-3fb94102b6a6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2f7b20c3-7b94-4149-b740-3fb94102b6a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2de9f433-9c34-4e2a-9a6f-74bf9de57513" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2f7b20c3-7b94-4149-b740-3fb94102b6a6" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2de9f433-9c34-4e2a-9a6f-74bf9de57513" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CoreDepositsMember_b25b2ca7-4661-406b-8c13-ce1323bc882e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CoreDepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2de9f433-9c34-4e2a-9a6f-74bf9de57513" xlink:to="loc_us-gaap_CoreDepositsMember_b25b2ca7-4661-406b-8c13-ce1323bc882e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AcquisitionsPurchasedAssetsandAssumedLiabilitiesDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AcquisitionsPurchasedAssetsandAssumedLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AcquisitionsPurchasedAssetsandAssumedLiabilitiesDetails" xlink:type="extended" id="i3ba5152ee55f4d55978d0f5959551d0f_AcquisitionsPurchasedAssetsandAssumedLiabilitiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_e6efb184-1c17-4255-93df-7c0c56c244f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_e6efb184-1c17-4255-93df-7c0c56c244f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities_fbd458a5-2e96-4233-b139-b07b40e978e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsMarketableSecurities_fbd458a5-2e96-4233-b139-b07b40e978e7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansHeldForSale_0e1c136a-80ba-42ca-8900-d46f40912685" xlink:href="ucbi-20230331.xsd#ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansHeldForSale_0e1c136a-80ba-42ca-8900-d46f40912685" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_51c78ddc-573f-44e9-9d39-bbd1744ae29d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_51c78ddc-573f-44e9-9d39-bbd1744ae29d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_9d413046-9308-4dbd-8c81-5c541a994b04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_9d413046-9308-4dbd-8c81-5c541a994b04" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedBankOwnedLifeInsurance_a4b4923b-3008-4233-87d1-eebbe8e9497f" xlink:href="ucbi-20230331.xsd#ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedBankOwnedLifeInsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedBankOwnedLifeInsurance_a4b4923b-3008-4233-87d1-eebbe8e9497f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_b7468d98-5881-4ede-9426-a34f7996ad52" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_b7468d98-5881-4ede-9426-a34f7996ad52" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_50f499ff-51e3-47da-bb17-edc67dbfe63b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_50f499ff-51e3-47da-bb17-edc67dbfe63b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_3efb21e5-bf1e-4325-9647-093f9184363b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract_f9389595-cf27-412c-96d5-152fae9e1ca9" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_3efb21e5-bf1e-4325-9647-093f9184363b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_23950479-e335-48c9-bb70-a2f4c9976008" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_23950479-e335-48c9-bb70-a2f4c9976008" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits_dc6e1ce4-58bd-410e-bf12-f5a7f0ee4dd3" xlink:href="ucbi-20230331.xsd#ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_23950479-e335-48c9-bb70-a2f4c9976008" xlink:to="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits_dc6e1ce4-58bd-410e-bf12-f5a7f0ee4dd3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermBorrowings_a3a38485-76c1-4760-ba9d-2f6d689a33b3" xlink:href="ucbi-20230331.xsd#ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_23950479-e335-48c9-bb70-a2f4c9976008" xlink:to="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermBorrowings_a3a38485-76c1-4760-ba9d-2f6d689a33b3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFederalHomeLoanBankAdvances_df52a4d5-52bc-4ddc-840f-4079298f8d30" xlink:href="ucbi-20230331.xsd#ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFederalHomeLoanBankAdvances"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_23950479-e335-48c9-bb70-a2f4c9976008" xlink:to="loc_ucbi_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFederalHomeLoanBankAdvances_df52a4d5-52bc-4ddc-840f-4079298f8d30" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_2e848656-6a6b-45d9-b162-e543f1bcf909" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_23950479-e335-48c9-bb70-a2f4c9976008" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_2e848656-6a6b-45d9-b162-e543f1bcf909" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_f9bab73f-db9b-4d13-b61d-3b396dcee5d5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract_23950479-e335-48c9-bb70-a2f4c9976008" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_f9bab73f-db9b-4d13-b61d-3b396dcee5d5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_4ae5546a-3576-43bc-b072-23ecd9c216f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_4ae5546a-3576-43bc-b072-23ecd9c216f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_3817e992-bedd-4757-899c-7b492b28e495" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_3817e992-bedd-4757-899c-7b492b28e495" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_3cff08c3-0e3f-4771-bfd6-db101ae8db76" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_3cff08c3-0e3f-4771-bfd6-db101ae8db76" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BusinessCombinationConsiderationTransferredConvertedStockOptions_3f9eba92-883b-4c94-9ba5-5e355232823d" xlink:href="ucbi-20230331.xsd#ucbi_BusinessCombinationConsiderationTransferredConvertedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_ucbi_BusinessCombinationConsiderationTransferredConvertedStockOptions_3f9eba92-883b-4c94-9ba5-5e355232823d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_be35ab94-9689-4eb5-be02-c7a56cc62e0d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_be35ab94-9689-4eb5-be02-c7a56cc62e0d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_e2eaf282-57c3-40f7-99fb-12da1a4fa5b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_Goodwill_e2eaf282-57c3-40f7-99fb-12da1a4fa5b6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_57a43c6e-ea7a-4ba2-a13f-f2c8afeea12d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_57a43c6e-ea7a-4ba2-a13f-f2c8afeea12d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e452cad1-8123-4dd9-9db2-7011679bc81e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_61034caf-bf82-4ac2-937f-406a5163a8e8" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e452cad1-8123-4dd9-9db2-7011679bc81e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_bb2a0ea8-810b-4863-b643-aca9f4cfd2ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e452cad1-8123-4dd9-9db2-7011679bc81e" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_bb2a0ea8-810b-4863-b643-aca9f4cfd2ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bb2a0ea8-810b-4863-b643-aca9f4cfd2ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_bb2a0ea8-810b-4863-b643-aca9f4cfd2ba" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bb2a0ea8-810b-4863-b643-aca9f4cfd2ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a6e1ef49-89c6-40fd-9618-5f49e24200d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_bb2a0ea8-810b-4863-b643-aca9f4cfd2ba" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a6e1ef49-89c6-40fd-9618-5f49e24200d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ProgressBankTrustMember_5a87e0c8-1e78-4376-8fc0-b77435ae6e5f" xlink:href="ucbi-20230331.xsd#ucbi_ProgressBankTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a6e1ef49-89c6-40fd-9618-5f49e24200d9" xlink:to="loc_ucbi_ProgressBankTrustMember_5a87e0c8-1e78-4376-8fc0-b77435ae6e5f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AcquisitionsAcquiredLoanPortfolioatAcquisitionDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AcquisitionsAcquiredLoanPortfolioatAcquisitionDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AcquisitionsAcquiredLoanPortfolioatAcquisitionDetails" xlink:type="extended" id="i107247a530f349469cec63142bdaba45_AcquisitionsAcquiredLoanPortfolioatAcquisitionDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_cdd20045-e7a8-41f9-b657-b3afc7070b00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePriceAbstract_15c3b272-c519-4540-891c-5f8f44391b94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePriceAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cdd20045-e7a8-41f9-b657-b3afc7070b00" xlink:to="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePriceAbstract_15c3b272-c519-4540-891c-5f8f44391b94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtParValue_988c5deb-4d30-4217-9e13-c0bd3d3b211d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtParValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePriceAbstract_15c3b272-c519-4540-891c-5f8f44391b94" xlink:to="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtParValue_988c5deb-4d30-4217-9e13-c0bd3d3b211d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestPurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate_21bc5083-4cdc-4c71-a709-77dc63ffe0b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestPurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePriceAbstract_15c3b272-c519-4540-891c-5f8f44391b94" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestPurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate_21bc5083-4cdc-4c71-a709-77dc63ffe0b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationDiscountPremium_20e60ef0-394b-4f9a-8532-23604e68a4d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationDiscountPremium"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePriceAbstract_15c3b272-c519-4540-891c-5f8f44391b94" xlink:to="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationDiscountPremium_20e60ef0-394b-4f9a-8532-23604e68a4d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice_8c885f45-2841-4e29-a24d-b34f6a82ab67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePriceAbstract_15c3b272-c519-4540-891c-5f8f44391b94" xlink:to="loc_us-gaap_FinancingReceivablePurchasedWithCreditDeteriorationAmountAtPurchasePrice_8c885f45-2841-4e29-a24d-b34f6a82ab67" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquiredReceivablesAbstract_d6a4e039-fdb2-4b02-82cd-980eecb395c7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquiredReceivablesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cdd20045-e7a8-41f9-b657-b3afc7070b00" xlink:to="loc_us-gaap_BusinessCombinationAcquiredReceivablesAbstract_d6a4e039-fdb2-4b02-82cd-980eecb395c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquiredReceivablesFairValue_bec06c50-8ba6-4009-b0f7-826ef4091092" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquiredReceivablesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationAcquiredReceivablesAbstract_d6a4e039-fdb2-4b02-82cd-980eecb395c7" xlink:to="loc_us-gaap_BusinessCombinationAcquiredReceivablesFairValue_bec06c50-8ba6-4009-b0f7-826ef4091092" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquiredReceivablesGrossContractualAmount_eb89a462-36e9-4aeb-8424-c5c635fd723c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquiredReceivablesGrossContractualAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationAcquiredReceivablesAbstract_d6a4e039-fdb2-4b02-82cd-980eecb395c7" xlink:to="loc_us-gaap_BusinessCombinationAcquiredReceivablesGrossContractualAmount_eb89a462-36e9-4aeb-8424-c5c635fd723c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquiredReceivablesEstimatedUncollectible_7b15cbe3-43af-4414-af11-2cd5062a14ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquiredReceivablesEstimatedUncollectible"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationAcquiredReceivablesAbstract_d6a4e039-fdb2-4b02-82cd-980eecb395c7" xlink:to="loc_us-gaap_BusinessCombinationAcquiredReceivablesEstimatedUncollectible_7b15cbe3-43af-4414-af11-2cd5062a14ec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_f3475d3f-61e7-46a0-9051-1ed8b8fd3031" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cdd20045-e7a8-41f9-b657-b3afc7070b00" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_f3475d3f-61e7-46a0-9051-1ed8b8fd3031" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_a656ddde-2a83-442d-a762-c61c7fadd944" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_f3475d3f-61e7-46a0-9051-1ed8b8fd3031" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_a656ddde-2a83-442d-a762-c61c7fadd944" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a656ddde-2a83-442d-a762-c61c7fadd944_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a656ddde-2a83-442d-a762-c61c7fadd944" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a656ddde-2a83-442d-a762-c61c7fadd944_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_80e93179-ff07-4d97-906f-adf8f5cc4a2a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a656ddde-2a83-442d-a762-c61c7fadd944" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_80e93179-ff07-4d97-906f-adf8f5cc4a2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ProgressBankTrustMember_8a620c8a-1af0-41d5-bb36-25dfb236f671" xlink:href="ucbi-20230331.xsd#ucbi_ProgressBankTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_80e93179-ff07-4d97-906f-adf8f5cc4a2a" xlink:to="loc_ucbi_ProgressBankTrustMember_8a620c8a-1af0-41d5-bb36-25dfb236f671" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditLossStatusAxis_3eedc280-b19b-479d-8f82-b902ad17a268" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditLossStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_f3475d3f-61e7-46a0-9051-1ed8b8fd3031" xlink:to="loc_us-gaap_CreditLossStatusAxis_3eedc280-b19b-479d-8f82-b902ad17a268" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditLossStatusDomain_3eedc280-b19b-479d-8f82-b902ad17a268_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditLossStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditLossStatusAxis_3eedc280-b19b-479d-8f82-b902ad17a268" xlink:to="loc_us-gaap_CreditLossStatusDomain_3eedc280-b19b-479d-8f82-b902ad17a268_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditLossStatusDomain_f8803df9-eb75-4d7f-8050-ac4bceb81545" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditLossStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditLossStatusAxis_3eedc280-b19b-479d-8f82-b902ad17a268" xlink:to="loc_us-gaap_CreditLossStatusDomain_f8803df9-eb75-4d7f-8050-ac4bceb81545" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember_e64c7c6a-b377-4a7b-96ae-98d8fe77c436" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditLossStatusDomain_f8803df9-eb75-4d7f-8050-ac4bceb81545" xlink:to="loc_us-gaap_FinancialAssetAcquiredWithCreditDeteriorationMember_e64c7c6a-b377-4a7b-96ae-98d8fe77c436" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AcquisitionsProFormaInformationDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AcquisitionsProFormaInformationDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AcquisitionsProFormaInformationDetails" xlink:type="extended" id="i8713d82c2b6e43bcbfea1b3c4ccb8426_AcquisitionsProFormaInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_b78b7c92-f3f5-4b90-a383-445f4f786462" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_c34a279e-e1a7-4b9b-836f-adead1154f78" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b78b7c92-f3f5-4b90-a383-445f4f786462" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_c34a279e-e1a7-4b9b-836f-adead1154f78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_edc248b3-2467-4329-b1c7-0c43861ffbda" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b78b7c92-f3f5-4b90-a383-445f4f786462" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_edc248b3-2467-4329-b1c7-0c43861ffbda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_7e1ce077-672a-4aee-85e3-8df05f76586b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b78b7c92-f3f5-4b90-a383-445f4f786462" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_7e1ce077-672a-4aee-85e3-8df05f76586b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_6b5377b4-57db-40bf-88f7-4c93ce0b7cd1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b78b7c92-f3f5-4b90-a383-445f4f786462" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_6b5377b4-57db-40bf-88f7-4c93ce0b7cd1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8b312f8f-71eb-419a-b10f-141a50712945" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_b78b7c92-f3f5-4b90-a383-445f4f786462" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8b312f8f-71eb-419a-b10f-141a50712945" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_368c8373-f37b-4e17-8179-1bf67b04c85b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8b312f8f-71eb-419a-b10f-141a50712945" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_368c8373-f37b-4e17-8179-1bf67b04c85b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_368c8373-f37b-4e17-8179-1bf67b04c85b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_368c8373-f37b-4e17-8179-1bf67b04c85b" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_368c8373-f37b-4e17-8179-1bf67b04c85b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1bb62322-e559-4ece-b297-a0b2e08170ad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_368c8373-f37b-4e17-8179-1bf67b04c85b" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1bb62322-e559-4ece-b297-a0b2e08170ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ProgressBankTrustMember_c2030724-e6d9-4f69-8794-2f6db48f7159" xlink:href="ucbi-20230331.xsd#ucbi_ProgressBankTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1bb62322-e559-4ece-b297-a0b2e08170ad" xlink:to="loc_ucbi_ProgressBankTrustMember_c2030724-e6d9-4f69-8794-2f6db48f7159" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ReliantBancorpIncMember_4edc71ae-812e-4946-9aee-3e992621f9ee" xlink:href="ucbi-20230331.xsd#ucbi_ReliantBancorpIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1bb62322-e559-4ece-b297-a0b2e08170ad" xlink:to="loc_ucbi_ReliantBancorpIncMember_4edc71ae-812e-4946-9aee-3e992621f9ee" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/InvestmentSecuritiesAmortizedCostBasisUnrealizedGainsandLossesandFairvalueofHTMDebtSecuritiesDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#InvestmentSecuritiesAmortizedCostBasisUnrealizedGainsandLossesandFairvalueofHTMDebtSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/InvestmentSecuritiesAmortizedCostBasisUnrealizedGainsandLossesandFairvalueofHTMDebtSecuritiesDetails" xlink:type="extended" id="i7e623801debe45a7afb7eec8e551fc5e_InvestmentSecuritiesAmortizedCostBasisUnrealizedGainsandLossesandFairvalueofHTMDebtSecuritiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_c07bc14f-52f2-4621-8331-5ef86cf1093f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAbstract_423102dc-dd5d-4f9c-b2c8-89759d44cdc4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_c07bc14f-52f2-4621-8331-5ef86cf1093f" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAbstract_423102dc-dd5d-4f9c-b2c8-89759d44cdc4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_5a7a6dcb-d7b6-433a-af9b-bbf26cf0a012" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesAbstract_423102dc-dd5d-4f9c-b2c8-89759d44cdc4" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_5a7a6dcb-d7b6-433a-af9b-bbf26cf0a012" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain_bf027f84-9b6f-4d5e-b66b-71ae5e31591a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesAbstract_423102dc-dd5d-4f9c-b2c8-89759d44cdc4" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain_bf027f84-9b6f-4d5e-b66b-71ae5e31591a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss_14fdca1e-9d34-4d09-8709-7cdde4d86f98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesAbstract_423102dc-dd5d-4f9c-b2c8-89759d44cdc4" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss_14fdca1e-9d34-4d09-8709-7cdde4d86f98" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_a2539ae5-718b-4ddd-aee2-d41e661e8279" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesAbstract_423102dc-dd5d-4f9c-b2c8-89759d44cdc4" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_a2539ae5-718b-4ddd-aee2-d41e661e8279" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_a6cb1ed5-43be-4849-a68d-4f36e89a893b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_c07bc14f-52f2-4621-8331-5ef86cf1093f" xlink:to="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_a6cb1ed5-43be-4849-a68d-4f36e89a893b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_771f7c4e-b74c-44ce-9fca-0843396b814f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_a6cb1ed5-43be-4849-a68d-4f36e89a893b" xlink:to="loc_us-gaap_FinancialInstrumentAxis_771f7c4e-b74c-44ce-9fca-0843396b814f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_771f7c4e-b74c-44ce-9fca-0843396b814f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_771f7c4e-b74c-44ce-9fca-0843396b814f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_771f7c4e-b74c-44ce-9fca-0843396b814f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9a530feb-4529-4c25-a3ff-772f255cc666" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_771f7c4e-b74c-44ce-9fca-0843396b814f" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9a530feb-4529-4c25-a3ff-772f255cc666" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_0c63722c-00c9-45e1-9cc0-939eb0dca234" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9a530feb-4529-4c25-a3ff-772f255cc666" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_0c63722c-00c9-45e1-9cc0-939eb0dca234" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_5429e39c-1b88-4cb1-b846-83f691ccfebe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9a530feb-4529-4c25-a3ff-772f255cc666" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_5429e39c-1b88-4cb1-b846-83f691ccfebe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_9494644b-8e3c-4e2e-8eb2-734067ed4729" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9a530feb-4529-4c25-a3ff-772f255cc666" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_9494644b-8e3c-4e2e-8eb2-734067ed4729" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_a7ceb6a4-1b9a-4d84-98f1-7203301e06fc" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9a530feb-4529-4c25-a3ff-772f255cc666" xlink:to="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_a7ceb6a4-1b9a-4d84-98f1-7203301e06fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_5c48e20e-c2a3-4d1d-bc27-9b85e9cfeb25" xlink:href="ucbi-20230331.xsd#ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9a530feb-4529-4c25-a3ff-772f255cc666" xlink:to="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_5c48e20e-c2a3-4d1d-bc27-9b85e9cfeb25" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDebtSecuritiesMember_0981f177-793c-49d2-8ea5-78a8a13bb6de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9a530feb-4529-4c25-a3ff-772f255cc666" xlink:to="loc_us-gaap_OtherDebtSecuritiesMember_0981f177-793c-49d2-8ea5-78a8a13bb6de" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/InvestmentSecuritiesNarrativeDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#InvestmentSecuritiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/InvestmentSecuritiesNarrativeDetails" xlink:type="extended" id="i77e69c99761e40bd8fa7e8e359be46df_InvestmentSecuritiesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityLineItems_5afe03e8-ec71-46d5-a409-7d51ca4941dc" xlink:href="ucbi-20230331.xsd#ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturity_37d38721-f003-408d-a999-aa05759c02ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityLineItems_5afe03e8-ec71-46d5-a409-7d51ca4941dc" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturity_37d38721-f003-408d-a999-aa05759c02ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityTable_42b65e0d-a86f-4450-aeb7-d37d9eb5bf4e" xlink:href="ucbi-20230331.xsd#ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityLineItems_5afe03e8-ec71-46d5-a409-7d51ca4941dc" xlink:to="loc_ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityTable_42b65e0d-a86f-4450-aeb7-d37d9eb5bf4e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusAxis_d1e4d296-ccca-4c85-96fa-e397b033c321" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PledgedStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityTable_42b65e0d-a86f-4450-aeb7-d37d9eb5bf4e" xlink:to="loc_us-gaap_PledgedStatusAxis_d1e4d296-ccca-4c85-96fa-e397b033c321" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_d1e4d296-ccca-4c85-96fa-e397b033c321_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgedStatusAxis_d1e4d296-ccca-4c85-96fa-e397b033c321" xlink:to="loc_us-gaap_PledgedStatusDomain_d1e4d296-ccca-4c85-96fa-e397b033c321_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgedStatusDomain_d844f6d5-455c-4871-a593-d4e3c0182f2c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PledgedStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgedStatusAxis_d1e4d296-ccca-4c85-96fa-e397b033c321" xlink:to="loc_us-gaap_PledgedStatusDomain_d844f6d5-455c-4871-a593-d4e3c0182f2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetPledgedAsCollateralMember_cf25efba-d378-4672-8f32-d170c77a9e0a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetPledgedAsCollateralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgedStatusDomain_d844f6d5-455c-4871-a593-d4e3c0182f2c" xlink:to="loc_us-gaap_AssetPledgedAsCollateralMember_cf25efba-d378-4672-8f32-d170c77a9e0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgingPurposeAxis_c0ed69e6-216e-4531-a8ca-aabed74298a6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PledgingPurposeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_ucbi_DebtSecuritiesAvailableForSaleAndHeldToMaturityTable_42b65e0d-a86f-4450-aeb7-d37d9eb5bf4e" xlink:to="loc_us-gaap_PledgingPurposeAxis_c0ed69e6-216e-4531-a8ca-aabed74298a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgingPurposeDomain_c0ed69e6-216e-4531-a8ca-aabed74298a6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PledgingPurposeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PledgingPurposeAxis_c0ed69e6-216e-4531-a8ca-aabed74298a6" xlink:to="loc_us-gaap_PledgingPurposeDomain_c0ed69e6-216e-4531-a8ca-aabed74298a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PledgingPurposeDomain_3792b44b-aca9-40f6-a840-101d89626bfe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PledgingPurposeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PledgingPurposeAxis_c0ed69e6-216e-4531-a8ca-aabed74298a6" xlink:to="loc_us-gaap_PledgingPurposeDomain_3792b44b-aca9-40f6-a840-101d89626bfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsMember_60865e7f-ec60-4a66-8c2e-403accbb1509" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PledgingPurposeDomain_3792b44b-aca9-40f6-a840-101d89626bfe" xlink:to="loc_us-gaap_DepositsMember_60865e7f-ec60-4a66-8c2e-403accbb1509" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/InvestmentSecuritiesAmortizedCostBasisUnrealizedGainsandLossesandFairValueofAFSDebtSecuritiesDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#InvestmentSecuritiesAmortizedCostBasisUnrealizedGainsandLossesandFairValueofAFSDebtSecuritiesDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/InvestmentSecuritiesAmortizedCostBasisUnrealizedGainsandLossesandFairValueofAFSDebtSecuritiesDetails" xlink:type="extended" id="i49a34fd5f504480aa45e7d8691463dd8_InvestmentSecuritiesAmortizedCostBasisUnrealizedGainsandLossesandFairValueofAFSDebtSecuritiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_4c4321b3-be67-44bd-a902-325e531fbad1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesAbstract_aa4841f1-faec-4562-88a6-cc0e4453288c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_4c4321b3-be67-44bd-a902-325e531fbad1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesAbstract_aa4841f1-faec-4562-88a6-cc0e4453288c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_34c1eeb0-d461-4a9a-b84a-9119243cdf14" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesAbstract_aa4841f1-faec-4562-88a6-cc0e4453288c" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_34c1eeb0-d461-4a9a-b84a-9119243cdf14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_ddaafb35-db28-4e15-8ca2-155bd464e467" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesAbstract_aa4841f1-faec-4562-88a6-cc0e4453288c" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_ddaafb35-db28-4e15-8ca2-155bd464e467" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_0770e379-b993-4057-892d-dff1c8438dcc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesAbstract_aa4841f1-faec-4562-88a6-cc0e4453288c" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_0770e379-b993-4057-892d-dff1c8438dcc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_37c02e14-23b5-475c-9fdc-9127ce576bef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesAbstract_aa4841f1-faec-4562-88a6-cc0e4453288c" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_37c02e14-23b5-475c-9fdc-9127ce576bef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_cec19b59-3048-4aa0-80bb-48400589ecb4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_4c4321b3-be67-44bd-a902-325e531fbad1" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_cec19b59-3048-4aa0-80bb-48400589ecb4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_55510b68-72bd-4d43-aed8-6d0ce1a2e569" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_cec19b59-3048-4aa0-80bb-48400589ecb4" xlink:to="loc_us-gaap_FinancialInstrumentAxis_55510b68-72bd-4d43-aed8-6d0ce1a2e569" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_55510b68-72bd-4d43-aed8-6d0ce1a2e569_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_55510b68-72bd-4d43-aed8-6d0ce1a2e569" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_55510b68-72bd-4d43-aed8-6d0ce1a2e569_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_55510b68-72bd-4d43-aed8-6d0ce1a2e569" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_8c9d1348-d0c7-472e-9517-a37075969f22" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_8c9d1348-d0c7-472e-9517-a37075969f22" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_4aabb7c6-6e51-49f0-b676-e2d70de01376" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_4aabb7c6-6e51-49f0-b676-e2d70de01376" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_003d8b45-f120-4e21-a90b-148c241f22b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_003d8b45-f120-4e21-a90b-148c241f22b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_86264744-00da-48e4-a59e-71bcf06ff7bd" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_86264744-00da-48e4-a59e-71bcf06ff7bd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_3dff2f0a-5305-4aec-b8a7-fec01644166f" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_3dff2f0a-5305-4aec-b8a7-fec01644166f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_9b9e4fda-28df-42b9-92e6-0595872cfdbe" xlink:href="ucbi-20230331.xsd#ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_9b9e4fda-28df-42b9-92e6-0595872cfdbe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_719ca31b-dcfe-4340-af0e-94e3c78f8965" xlink:href="ucbi-20230331.xsd#ucbi_CommercialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_719ca31b-dcfe-4340-af0e-94e3c78f8965" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_157bcede-4909-41ca-b076-b2645c07f52b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_157bcede-4909-41ca-b076-b2645c07f52b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_8fc09a50-f97a-4f73-81cc-cfe499589dc0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b0c01096-5f6c-4b4c-9a2b-d3e29535f001" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_8fc09a50-f97a-4f73-81cc-cfe499589dc0" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/InvestmentSecuritiesHTMDebtSecuritiesinUnrealizedLossPositionDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#InvestmentSecuritiesHTMDebtSecuritiesinUnrealizedLossPositionDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/InvestmentSecuritiesHTMDebtSecuritiesinUnrealizedLossPositionDetails" xlink:type="extended" id="ia1814e1f77024e508b22e3457e0739ef_InvestmentSecuritiesHTMDebtSecuritiesinUnrealizedLossPositionDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_bde5b933-8253-4273-9e8e-880f844f6217" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_342997f1-0f9a-42ba-9ac2-99a677d5777b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_bde5b933-8253-4273-9e8e-880f844f6217" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_342997f1-0f9a-42ba-9ac2-99a677d5777b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_e0fa1d30-3aeb-414e-a976-0f419f1cfe90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_342997f1-0f9a-42ba-9ac2-99a677d5777b" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue_e0fa1d30-3aeb-414e-a976-0f419f1cfe90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_cf1efb78-d893-4da2-a7ae-ff1bdf11cef2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_342997f1-0f9a-42ba-9ac2-99a677d5777b" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_cf1efb78-d893-4da2-a7ae-ff1bdf11cef2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_7f8b3dc1-da39-4836-b67c-27b5ac6d77fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_342997f1-0f9a-42ba-9ac2-99a677d5777b" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue_7f8b3dc1-da39-4836-b67c-27b5ac6d77fd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_bbb8a371-ddd6-4f29-a22d-0f9758dbbba4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_342997f1-0f9a-42ba-9ac2-99a677d5777b" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_bbb8a371-ddd6-4f29-a22d-0f9758dbbba4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue_c04759f0-6c6f-4ef2-a093-6c5235f0b90d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_342997f1-0f9a-42ba-9ac2-99a677d5777b" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue_c04759f0-6c6f-4ef2-a093-6c5235f0b90d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss_7354f114-ead8-403d-ba75-65445c781fce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAbstract_342997f1-0f9a-42ba-9ac2-99a677d5777b" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss_7354f114-ead8-403d-ba75-65445c781fce" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_4d14a89d-076e-4d4e-91b0-336d3cb729b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfHeldToMaturitySecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesLineItems_bde5b933-8253-4273-9e8e-880f844f6217" xlink:to="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_4d14a89d-076e-4d4e-91b0-336d3cb729b9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_7b527b63-8df0-42ca-882a-0e94b0ce73d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfHeldToMaturitySecuritiesTable_4d14a89d-076e-4d4e-91b0-336d3cb729b9" xlink:to="loc_us-gaap_FinancialInstrumentAxis_7b527b63-8df0-42ca-882a-0e94b0ce73d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7b527b63-8df0-42ca-882a-0e94b0ce73d9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7b527b63-8df0-42ca-882a-0e94b0ce73d9" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7b527b63-8df0-42ca-882a-0e94b0ce73d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e9c9da13-462b-4e76-8092-d281b1b75b4b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7b527b63-8df0-42ca-882a-0e94b0ce73d9" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e9c9da13-462b-4e76-8092-d281b1b75b4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_ab137d62-520f-4ad0-9438-3492087e9b92" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e9c9da13-462b-4e76-8092-d281b1b75b4b" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_ab137d62-520f-4ad0-9438-3492087e9b92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_9ad46495-a853-460a-b545-dc5754a4a652" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e9c9da13-462b-4e76-8092-d281b1b75b4b" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_9ad46495-a853-460a-b545-dc5754a4a652" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_6cbf2e13-88d7-42af-aa01-1d75b5172a8c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e9c9da13-462b-4e76-8092-d281b1b75b4b" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_6cbf2e13-88d7-42af-aa01-1d75b5172a8c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_57c29e5a-0493-4a86-acff-e31f22947b1c" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e9c9da13-462b-4e76-8092-d281b1b75b4b" xlink:to="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_57c29e5a-0493-4a86-acff-e31f22947b1c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_fbf19e28-5fce-49a9-b147-72ef12678e02" xlink:href="ucbi-20230331.xsd#ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e9c9da13-462b-4e76-8092-d281b1b75b4b" xlink:to="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_fbf19e28-5fce-49a9-b147-72ef12678e02" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDebtSecuritiesMember_0ff3370d-f26f-41c8-9e86-193bcd68d5b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e9c9da13-462b-4e76-8092-d281b1b75b4b" xlink:to="loc_us-gaap_OtherDebtSecuritiesMember_0ff3370d-f26f-41c8-9e86-193bcd68d5b4" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/InvestmentSecuritiesAFSDebtSecuritiesinUnrealizedLossPositionDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#InvestmentSecuritiesAFSDebtSecuritiesinUnrealizedLossPositionDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/InvestmentSecuritiesAFSDebtSecuritiesinUnrealizedLossPositionDetails" xlink:type="extended" id="i48e034d7be9b465fb052d9f304e9010b_InvestmentSecuritiesAFSDebtSecuritiesinUnrealizedLossPositionDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_592c0b74-b01b-4a80-a6e6-8228b57bbe60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_cdb0a607-903a-471e-bd45-b4eb7116cd75" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_592c0b74-b01b-4a80-a6e6-8228b57bbe60" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_cdb0a607-903a-471e-bd45-b4eb7116cd75" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_33920c8e-5c14-4051-8844-b47ed7f48eef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_cdb0a607-903a-471e-bd45-b4eb7116cd75" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_33920c8e-5c14-4051-8844-b47ed7f48eef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_f8a70cb2-f24b-43f1-97cd-f075e1138397" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_cdb0a607-903a-471e-bd45-b4eb7116cd75" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_f8a70cb2-f24b-43f1-97cd-f075e1138397" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_91bca41e-3919-434f-84e4-52e8e4497a97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_cdb0a607-903a-471e-bd45-b4eb7116cd75" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_91bca41e-3919-434f-84e4-52e8e4497a97" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_7015d6be-9a4d-45e1-bd0d-8285857fa5e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_cdb0a607-903a-471e-bd45-b4eb7116cd75" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_7015d6be-9a4d-45e1-bd0d-8285857fa5e2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_502f56f9-d0f6-4c76-8e7b-b737e0d1153e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_cdb0a607-903a-471e-bd45-b4eb7116cd75" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_502f56f9-d0f6-4c76-8e7b-b737e0d1153e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_17353854-2a93-414a-94e0-bb9547a3dc64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLossAbstract_cdb0a607-903a-471e-bd45-b4eb7116cd75" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_17353854-2a93-414a-94e0-bb9547a3dc64" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_1c7705c8-08ef-4937-b231-42ae01e7ff6d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_592c0b74-b01b-4a80-a6e6-8228b57bbe60" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_1c7705c8-08ef-4937-b231-42ae01e7ff6d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_da3fd846-b08a-4834-9dad-7d946cf7926a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_1c7705c8-08ef-4937-b231-42ae01e7ff6d" xlink:to="loc_us-gaap_FinancialInstrumentAxis_da3fd846-b08a-4834-9dad-7d946cf7926a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_da3fd846-b08a-4834-9dad-7d946cf7926a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_da3fd846-b08a-4834-9dad-7d946cf7926a" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_da3fd846-b08a-4834-9dad-7d946cf7926a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_da3fd846-b08a-4834-9dad-7d946cf7926a" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_3da17233-4597-4445-a1f3-2f69af038c25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_3da17233-4597-4445-a1f3-2f69af038c25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_d112f7f8-a7b1-4233-810d-4bfa5566ab09" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_d112f7f8-a7b1-4233-810d-4bfa5566ab09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_a315bc72-8d92-411f-8578-22f1def9691d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_a315bc72-8d92-411f-8578-22f1def9691d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_d979db61-091e-4c0d-b1c1-34d9966b1de1" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_d979db61-091e-4c0d-b1c1-34d9966b1de1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_4bc34d21-0c80-472e-b201-c2cecd0604b3" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_ucbi_ResidentialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_4bc34d21-0c80-472e-b201-c2cecd0604b3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_295bb62d-aa25-45d8-ac7c-cd125663f84d" xlink:href="ucbi-20230331.xsd#ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember_295bb62d-aa25-45d8-ac7c-cd125663f84d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_ae58e611-94e4-49e6-8d2e-305917e369db" xlink:href="ucbi-20230331.xsd#ucbi_CommercialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_ucbi_CommercialMortgageBackedSecuritiesIssuedByPrivateEnterprisesMember_ae58e611-94e4-49e6-8d2e-305917e369db" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_fa63d9cc-b1bd-4dd4-8c95-03bac1e6539b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_fa63d9cc-b1bd-4dd4-8c95-03bac1e6539b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_36282e1f-3008-4636-9a87-fdfbc10d9ab4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_61b35d73-0695-4fc8-9df7-54dd092e123d" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_36282e1f-3008-4636-9a87-fdfbc10d9ab4" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/InvestmentSecuritiesAccruedInterestReceivableDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#InvestmentSecuritiesAccruedInterestReceivableDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/InvestmentSecuritiesAccruedInterestReceivableDetails" xlink:type="extended" id="i3a1f7d3f96494b8383fb28d888dad4d2_InvestmentSecuritiesAccruedInterestReceivableDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_f2dbc810-94d9-4348-9bd2-e8f660c6ad5e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivableAndOtherAssetsAbstract_a7c18ae8-0439-494c-9fcd-2e8a32d40346" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestReceivableAndOtherAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_f2dbc810-94d9-4348-9bd2-e8f660c6ad5e" xlink:to="loc_us-gaap_InterestReceivableAndOtherAssetsAbstract_a7c18ae8-0439-494c-9fcd-2e8a32d40346" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivable_defe0217-ffec-4420-b17c-55c1f68d5e59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestReceivableAndOtherAssetsAbstract_a7c18ae8-0439-494c-9fcd-2e8a32d40346" xlink:to="loc_us-gaap_InterestReceivable_defe0217-ffec-4420-b17c-55c1f68d5e59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_704a4985-0840-4737-96c8-51fa287473d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_f2dbc810-94d9-4348-9bd2-e8f660c6ad5e" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_704a4985-0840-4737-96c8-51fa287473d9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_b70db1f5-a154-4d05-b3bb-c02bace7d42d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_704a4985-0840-4737-96c8-51fa287473d9" xlink:to="loc_us-gaap_FinancialInstrumentAxis_b70db1f5-a154-4d05-b3bb-c02bace7d42d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b70db1f5-a154-4d05-b3bb-c02bace7d42d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_b70db1f5-a154-4d05-b3bb-c02bace7d42d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b70db1f5-a154-4d05-b3bb-c02bace7d42d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bb62f0b-5ed1-4456-8858-8161d7ac299f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_b70db1f5-a154-4d05-b3bb-c02bace7d42d" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bb62f0b-5ed1-4456-8858-8161d7ac299f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DebtSecuritiesHeldToMaturityMember_d7fda468-e2d2-43e7-aca3-8188ae80d2f3" xlink:href="ucbi-20230331.xsd#ucbi_DebtSecuritiesHeldToMaturityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bb62f0b-5ed1-4456-8858-8161d7ac299f" xlink:to="loc_ucbi_DebtSecuritiesHeldToMaturityMember_d7fda468-e2d2-43e7-aca3-8188ae80d2f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DebtSecuritiesAvailableForSaleMember_7a46b72d-08a6-4b95-9b4a-48d79b9e7151" xlink:href="ucbi-20230331.xsd#ucbi_DebtSecuritiesAvailableForSaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_3bb62f0b-5ed1-4456-8858-8161d7ac299f" xlink:to="loc_ucbi_DebtSecuritiesAvailableForSaleMember_7a46b72d-08a6-4b95-9b4a-48d79b9e7151" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/InvestmentSecuritiesAmortizedCostandFairvalueofAFSandHTMDebtSecuritiesbyContractualMaturityDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#InvestmentSecuritiesAmortizedCostandFairvalueofAFSandHTMDebtSecuritiesbyContractualMaturityDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/InvestmentSecuritiesAmortizedCostandFairvalueofAFSandHTMDebtSecuritiesbyContractualMaturityDetails" xlink:type="extended" id="ib5efd0ce7358431a9d8ccd7955b8b026_InvestmentSecuritiesAmortizedCostandFairvalueofAFSandHTMDebtSecuritiesbyContractualMaturityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems_4b1662a0-f9de-4247-b750-7d45c92ad13f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract_87b384d4-d1b1-43ab-88ff-fe2f613246ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems_4b1662a0-f9de-4247-b750-7d45c92ad13f" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract_87b384d4-d1b1-43ab-88ff-fe2f613246ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis_a8302838-a9c6-47de-87f0-5f0c860aca44" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract_87b384d4-d1b1-43ab-88ff-fe2f613246ea" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis_a8302838-a9c6-47de-87f0-5f0c860aca44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis_3fea46b0-4b67-4919-aa63-9db834c0c23b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract_87b384d4-d1b1-43ab-88ff-fe2f613246ea" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis_3fea46b0-4b67-4919-aa63-9db834c0c23b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis_32f572b9-168f-42e3-a102-1cfaeb37c9c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract_87b384d4-d1b1-43ab-88ff-fe2f613246ea" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis_32f572b9-168f-42e3-a102-1cfaeb37c9c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis_8ecb8036-db94-4a9d-b5c3-3b99e83f6c71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract_87b384d4-d1b1-43ab-88ff-fe2f613246ea" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis_8ecb8036-db94-4a9d-b5c3-3b99e83f6c71" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost_3707b15a-ac04-4cfb-ad8e-2b1e4a2b4ae9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract_87b384d4-d1b1-43ab-88ff-fe2f613246ea" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost_3707b15a-ac04-4cfb-ad8e-2b1e4a2b4ae9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_3fd72900-f9a3-4404-b07b-72c2ce09e489" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesAmortizedCostBasisRollingMaturityAbstract_87b384d4-d1b1-43ab-88ff-fe2f613246ea" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLoss_3fd72900-f9a3-4404-b07b-72c2ce09e489" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_2b894c83-534f-43f0-be38-213870330544" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems_4b1662a0-f9de-4247-b750-7d45c92ad13f" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_2b894c83-534f-43f0-be38-213870330544" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue_6482c678-9f16-4e16-8146-e31757beb733" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_2b894c83-534f-43f0-be38-213870330544" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue_6482c678-9f16-4e16-8146-e31757beb733" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue_39546c30-6702-4134-8a1d-739491af8c85" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_2b894c83-534f-43f0-be38-213870330544" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue_39546c30-6702-4134-8a1d-739491af8c85" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue_40087076-83e8-49ff-8759-827ca9fdb5d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_2b894c83-534f-43f0-be38-213870330544" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue_40087076-83e8-49ff-8759-827ca9fdb5d1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue_aceba21b-5094-4b3d-8e27-7703be5fbf94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_2b894c83-534f-43f0-be38-213870330544" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue_aceba21b-5094-4b3d-8e27-7703be5fbf94" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_6bb59d92-b663-415a-8f93-56568da966cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_2b894c83-534f-43f0-be38-213870330544" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_6bb59d92-b663-415a-8f93-56568da966cf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_7cbb982a-af00-4855-9278-1d06c02527a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_2b894c83-534f-43f0-be38-213870330544" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_7cbb982a-af00-4855-9278-1d06c02527a4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract_04fbf087-09b0-4f7a-855e-d937f99fef9b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems_4b1662a0-f9de-4247-b750-7d45c92ad13f" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract_04fbf087-09b0-4f7a-855e-d937f99fef9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateYearOne_0b91c975-25fc-434e-9408-bbd0d9ce7274" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateYearOne"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract_04fbf087-09b0-4f7a-855e-d937f99fef9b" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateYearOne_0b91c975-25fc-434e-9408-bbd0d9ce7274" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYearOneThroughFive_c666d346-b0f8-4707-9e16-7711982f3059" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYearOneThroughFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract_04fbf087-09b0-4f7a-855e-d937f99fef9b" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYearOneThroughFive_c666d346-b0f8-4707-9e16-7711982f3059" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear5Through10_26e6c047-85e7-47d8-92c3-9bc678690260" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear5Through10"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract_04fbf087-09b0-4f7a-855e-d937f99fef9b" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear5Through10_26e6c047-85e7-47d8-92c3-9bc678690260" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear10_a2a57067-c5b0-46f1-98c4-3b9522a43d69" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear10"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract_04fbf087-09b0-4f7a-855e-d937f99fef9b" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityAllocatedAndSingleMaturityDateAfterYear10_a2a57067-c5b0-46f1-98c4-3b9522a43d69" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityWithoutSingleMaturityDate_f17687f0-8b39-4658-8ff6-4056dec02c05" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityWithoutSingleMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract_04fbf087-09b0-4f7a-855e-d937f99fef9b" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostExcludingAccruedInterestAfterAllowanceForCreditLossMaturityWithoutSingleMaturityDate_f17687f0-8b39-4658-8ff6-4056dec02c05" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_7b81dfa9-8b16-4f38-9daf-3299fb2d4b03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNetCarryingAmountAbstract_04fbf087-09b0-4f7a-855e-d937f99fef9b" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityExcludingAccruedInterestAfterAllowanceForCreditLoss_7b81dfa9-8b16-4f38-9daf-3299fb2d4b03" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_52631348-fd29-4252-ab77-eddb1168c5b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems_4b1662a0-f9de-4247-b750-7d45c92ad13f" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_52631348-fd29-4252-ab77-eddb1168c5b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue_97495315-5185-4cd3-963e-63358bfd33d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_52631348-fd29-4252-ab77-eddb1168c5b9" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue_97495315-5185-4cd3-963e-63358bfd33d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue_98d37a92-d878-4e23-af0b-da0377dc7e4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_52631348-fd29-4252-ab77-eddb1168c5b9" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue_98d37a92-d878-4e23-af0b-da0377dc7e4e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue_fa6f344d-c385-4c8e-aa17-6368d591fdef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_52631348-fd29-4252-ab77-eddb1168c5b9" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue_fa6f344d-c385-4c8e-aa17-6368d591fdef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue_77545733-06fa-46e6-8992-8ab8d8e56b44" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_52631348-fd29-4252-ab77-eddb1168c5b9" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesRollingAfterTenYearsFairValue_77545733-06fa-46e6-8992-8ab8d8e56b44" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_4d300006-21ab-4aeb-8f22-0cfddee74293" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_52631348-fd29-4252-ab77-eddb1168c5b9" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_4d300006-21ab-4aeb-8f22-0cfddee74293" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_a6f172ed-bca0-450c-bc20-60dc29b42b45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HeldToMaturitySecuritiesDebtMaturitiesFairValueRollingMaturityAbstract_52631348-fd29-4252-ab77-eddb1168c5b9" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_a6f172ed-bca0-450c-bc20-60dc29b42b45" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_3c8f2733-c8bd-43e6-b996-d7ff3fde5fdd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems_4b1662a0-f9de-4247-b750-7d45c92ad13f" xlink:to="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_3c8f2733-c8bd-43e6-b996-d7ff3fde5fdd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_da884fd3-6fcd-4992-99df-919df0d9e550" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsTable_3c8f2733-c8bd-43e6-b996-d7ff3fde5fdd" xlink:to="loc_us-gaap_FinancialInstrumentAxis_da884fd3-6fcd-4992-99df-919df0d9e550" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_da884fd3-6fcd-4992-99df-919df0d9e550_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_da884fd3-6fcd-4992-99df-919df0d9e550" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_da884fd3-6fcd-4992-99df-919df0d9e550_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_da884fd3-6fcd-4992-99df-919df0d9e550" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_cc74f0c7-619c-435b-bcd6-fa570141b7fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_cc74f0c7-619c-435b-bcd6-fa570141b7fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_f793f44d-7ebf-4697-9ed7-ff451a648497" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_f793f44d-7ebf-4697-9ed7-ff451a648497" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_29609894-187f-4225-abf4-ac0529469e25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_29609894-187f-4225-abf4-ac0529469e25" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_418bdb99-9930-48f2-a50c-ccffd603ec31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_418bdb99-9930-48f2-a50c-ccffd603ec31" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDebtSecuritiesMember_3e1b01eb-32d8-4c3d-8ab0-e7e5759df06f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:to="loc_us-gaap_OtherDebtSecuritiesMember_3e1b01eb-32d8-4c3d-8ab0-e7e5759df06f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_bb4611a1-5052-41a2-a2a9-94b4f4e8a4a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_bb4611a1-5052-41a2-a2a9-94b4f4e8a4a4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_185a43ec-3ad0-4181-8c27-77541c623d26" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_185a43ec-3ad0-4181-8c27-77541c623d26" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_a6adf1f7-df3f-4984-9cc3-bab39f680eb5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_ef90b56c-f4b6-4db9-a6fc-e1ac3bf44a85" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_a6adf1f7-df3f-4984-9cc3-bab39f680eb5" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesMajorclassificationsofloanportfolioDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#LoansandLeasesandAllowanceforCreditLossesMajorclassificationsofloanportfolioDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesMajorclassificationsofloanportfolioDetails" xlink:type="extended" id="ia2f7e6a879494f9fbfee4c7b4edff617_LoansandLeasesandAllowanceforCreditLossesMajorclassificationsofloanportfolioDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_078dcb24-5cd7-4140-8bfe-d636c96074b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableNetAbstract_9309d17a-311c-4035-87f0-cbf3ab6379f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotesReceivableNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_078dcb24-5cd7-4140-8bfe-d636c96074b1" xlink:to="loc_us-gaap_NotesReceivableNetAbstract_9309d17a-311c-4035-87f0-cbf3ab6379f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_ecfca1f1-25cd-4c28-9f32-633d8aa0b6b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NotesReceivableNetAbstract_9309d17a-311c-4035-87f0-cbf3ab6379f5" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_ecfca1f1-25cd-4c28-9f32-633d8aa0b6b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_12f50e02-5833-4df5-bcfe-f8b1be7e4089" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NotesReceivableNetAbstract_9309d17a-311c-4035-87f0-cbf3ab6379f5" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_12f50e02-5833-4df5-bcfe-f8b1be7e4089" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_11e38d45-f882-4719-b138-4727f458db42" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NotesReceivableNetAbstract_9309d17a-311c-4035-87f0-cbf3ab6379f5" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss_11e38d45-f882-4719-b138-4727f458db42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_12af411a-1786-4773-b5b6-ec8cbc1fb4a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_078dcb24-5cd7-4140-8bfe-d636c96074b1" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_12af411a-1786-4773-b5b6-ec8cbc1fb4a1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_882ff786-b050-4b11-a5b7-461e766ea387" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_12af411a-1786-4773-b5b6-ec8cbc1fb4a1" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_882ff786-b050-4b11-a5b7-461e766ea387" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_882ff786-b050-4b11-a5b7-461e766ea387_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_882ff786-b050-4b11-a5b7-461e766ea387" xlink:to="loc_us-gaap_ReceivableTypeDomain_882ff786-b050-4b11-a5b7-461e766ea387_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_92e12cfc-ef49-4315-ab68-94f92ee2a66b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_882ff786-b050-4b11-a5b7-461e766ea387" xlink:to="loc_us-gaap_ReceivableTypeDomain_92e12cfc-ef49-4315-ab68-94f92ee2a66b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableMember_3306650f-b06a-47ed-aa73-1cf20a1e6ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoansReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_92e12cfc-ef49-4315-ab68-94f92ee2a66b" xlink:to="loc_us-gaap_LoansReceivableMember_3306650f-b06a-47ed-aa73-1cf20a1e6ca5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_779c15b7-39d5-4a36-a516-dc90ffa436ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_12af411a-1786-4773-b5b6-ec8cbc1fb4a1" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_779c15b7-39d5-4a36-a516-dc90ffa436ea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_779c15b7-39d5-4a36-a516-dc90ffa436ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_779c15b7-39d5-4a36-a516-dc90ffa436ea" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_779c15b7-39d5-4a36-a516-dc90ffa436ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2853c5d4-6a2b-44d1-bfdd-79711bb3bdd7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_779c15b7-39d5-4a36-a516-dc90ffa436ea" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2853c5d4-6a2b-44d1-bfdd-79711bb3bdd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPortfolioSegmentMember_27611edb-7d38-4757-af40-603b2dabba44" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2853c5d4-6a2b-44d1-bfdd-79711bb3bdd7" xlink:to="loc_us-gaap_CommercialPortfolioSegmentMember_27611edb-7d38-4757-af40-603b2dabba44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_e69dd983-a322-4adf-a6e0-6236654c01a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2853c5d4-6a2b-44d1-bfdd-79711bb3bdd7" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_e69dd983-a322-4adf-a6e0-6236654c01a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_f71f6603-5e50-4ff4-8428-c9ae1dd372c6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2853c5d4-6a2b-44d1-bfdd-79711bb3bdd7" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_f71f6603-5e50-4ff4-8428-c9ae1dd372c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_b31be28a-e125-4635-a86f-63124e30b6a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_12af411a-1786-4773-b5b6-ec8cbc1fb4a1" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_b31be28a-e125-4635-a86f-63124e30b6a5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b31be28a-e125-4635-a86f-63124e30b6a5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_b31be28a-e125-4635-a86f-63124e30b6a5" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_b31be28a-e125-4635-a86f-63124e30b6a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_b31be28a-e125-4635-a86f-63124e30b6a5" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_7af8f4b8-13a7-4e0a-99ed-5f25f7ecb302" xlink:href="ucbi-20230331.xsd#ucbi_OwnerOccupiedCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:to="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_7af8f4b8-13a7-4e0a-99ed-5f25f7ecb302" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_IncomeProducingCommercialRealEstateMember_68a43a0c-8e01-44b9-891f-2053482dab70" xlink:href="ucbi-20230331.xsd#ucbi_IncomeProducingCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:to="loc_ucbi_IncomeProducingCommercialRealEstateMember_68a43a0c-8e01-44b9-891f-2053482dab70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialAndIndustrialClassificationMember_0754744c-19db-46ce-b46a-866166775dec" xlink:href="ucbi-20230331.xsd#ucbi_CommercialAndIndustrialClassificationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:to="loc_ucbi_CommercialAndIndustrialClassificationMember_0754744c-19db-46ce-b46a-866166775dec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionLoansMember_364ef25f-ab43-4a3e-a2ab-d76fe8ffc773" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:to="loc_us-gaap_ConstructionLoansMember_364ef25f-ab43-4a3e-a2ab-d76fe8ffc773" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EquipmentFinancingMember_877f05c3-a825-458c-9fe3-a8041992d89f" xlink:href="ucbi-20230331.xsd#ucbi_EquipmentFinancingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:to="loc_ucbi_EquipmentFinancingMember_877f05c3-a825-458c-9fe3-a8041992d89f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageMember_ef9ca64c-739c-4e2f-b53b-15683d9b654e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialMortgageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:to="loc_us-gaap_ResidentialMortgageMember_ef9ca64c-739c-4e2f-b53b-15683d9b654e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HomeEquityMember_ae522a38-6ed2-4902-a86d-66fd2a390122" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HomeEquityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:to="loc_us-gaap_HomeEquityMember_ae522a38-6ed2-4902-a86d-66fd2a390122" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ManufacturedHousingLoanMember_9c22b5ba-63d1-493a-8f53-9fb08a4f3ca0" xlink:href="ucbi-20230331.xsd#ucbi_ManufacturedHousingLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_5267415a-73fa-4d2b-bc4b-731c6a6a2524" xlink:to="loc_ucbi_ManufacturedHousingLoanMember_9c22b5ba-63d1-493a-8f53-9fb08a4f3ca0" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesNarrativeDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#LoansandLeasesandAllowanceforCreditLossesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesNarrativeDetails" xlink:type="extended" id="ibeba1d1c96c14bd2bbf83bb9bafdb95f_LoansandLeasesandAllowanceforCreditLossesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_6f410cb2-8f1e-4471-abd4-64c6c912dc41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivable_515820e2-7a94-4fec-aae1-08ec7a7192d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_6f410cb2-8f1e-4471-abd4-64c6c912dc41" xlink:to="loc_us-gaap_InterestReceivable_515820e2-7a94-4fec-aae1-08ec7a7192d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentInLease_713b6e88-fc7e-4332-b888-336e3515163a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetInvestmentInLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_6f410cb2-8f1e-4471-abd4-64c6c912dc41" xlink:to="loc_us-gaap_NetInvestmentInLease_713b6e88-fc7e-4332-b888-336e3515163a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FinancingReceivableModifiedExtensionFromModification_4318bacf-0da5-4bc7-9bf9-2070339edf09" xlink:href="ucbi-20230331.xsd#ucbi_FinancingReceivableModifiedExtensionFromModification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_6f410cb2-8f1e-4471-abd4-64c6c912dc41" xlink:to="loc_ucbi_FinancingReceivableModifiedExtensionFromModification_4318bacf-0da5-4bc7-9bf9-2070339edf09" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FinancingReceivableModifiedNumberOfExtensions_f872c71e-7479-4b5a-bb43-02e08400eef0" xlink:href="ucbi-20230331.xsd#ucbi_FinancingReceivableModifiedNumberOfExtensions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_6f410cb2-8f1e-4471-abd4-64c6c912dc41" xlink:to="loc_ucbi_FinancingReceivableModifiedNumberOfExtensions_f872c71e-7479-4b5a-bb43-02e08400eef0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableModifiedWeightedAverageInterestRateDecreaseFromModification_b0b3aee5-8b6b-4d82-bce9-3d8affd30a80" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableModifiedWeightedAverageInterestRateDecreaseFromModification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_6f410cb2-8f1e-4471-abd4-64c6c912dc41" xlink:to="loc_us-gaap_FinancingReceivableModifiedWeightedAverageInterestRateDecreaseFromModification_b0b3aee5-8b6b-4d82-bce9-3d8affd30a80" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableModifiedWeightedAverageTermIncreaseFromModification_4d7af72a-7983-46eb-a5ef-5ae4863eb9a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableModifiedWeightedAverageTermIncreaseFromModification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_6f410cb2-8f1e-4471-abd4-64c6c912dc41" xlink:to="loc_us-gaap_FinancingReceivableModifiedWeightedAverageTermIncreaseFromModification_4d7af72a-7983-46eb-a5ef-5ae4863eb9a7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a12c27c-65b6-4ac7-b0f1-a31762035679" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_6f410cb2-8f1e-4471-abd4-64c6c912dc41" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a12c27c-65b6-4ac7-b0f1-a31762035679" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_1c634e48-6036-4650-8b76-c55ea87b03be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a12c27c-65b6-4ac7-b0f1-a31762035679" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_1c634e48-6036-4650-8b76-c55ea87b03be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_1c634e48-6036-4650-8b76-c55ea87b03be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_1c634e48-6036-4650-8b76-c55ea87b03be" xlink:to="loc_us-gaap_ReceivableTypeDomain_1c634e48-6036-4650-8b76-c55ea87b03be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_8d6fd545-36c0-4f3e-a1ad-b48b223a8c44" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_1c634e48-6036-4650-8b76-c55ea87b03be" xlink:to="loc_us-gaap_ReceivableTypeDomain_8d6fd545-36c0-4f3e-a1ad-b48b223a8c44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableMember_13b500a1-e46f-48f6-bde9-6208d0e23970" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoansReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_8d6fd545-36c0-4f3e-a1ad-b48b223a8c44" xlink:to="loc_us-gaap_LoansReceivableMember_13b500a1-e46f-48f6-bde9-6208d0e23970" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationAxis_251d912d-b23e-4c45-b830-6afd752d26e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoanRestructuringModificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a12c27c-65b6-4ac7-b0f1-a31762035679" xlink:to="loc_us-gaap_LoanRestructuringModificationAxis_251d912d-b23e-4c45-b830-6afd752d26e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationDomain_251d912d-b23e-4c45-b830-6afd752d26e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoanRestructuringModificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LoanRestructuringModificationAxis_251d912d-b23e-4c45-b830-6afd752d26e4" xlink:to="loc_us-gaap_LoanRestructuringModificationDomain_251d912d-b23e-4c45-b830-6afd752d26e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationDomain_b0cf7b11-3c21-40e4-9b9e-52e43aca1fed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoanRestructuringModificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LoanRestructuringModificationAxis_251d912d-b23e-4c45-b830-6afd752d26e4" xlink:to="loc_us-gaap_LoanRestructuringModificationDomain_b0cf7b11-3c21-40e4-9b9e-52e43aca1fed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtendedMaturityMember_cd8e429e-b227-45d2-8f00-1f7f6fcca1f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExtendedMaturityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_b0cf7b11-3c21-40e4-9b9e-52e43aca1fed" xlink:to="loc_us-gaap_ExtendedMaturityMember_cd8e429e-b227-45d2-8f00-1f7f6fcca1f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentDeferralMember_9ba31e2b-fa3e-4b9d-8ca6-3bfe7fcb4d5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_b0cf7b11-3c21-40e4-9b9e-52e43aca1fed" xlink:to="loc_us-gaap_PaymentDeferralMember_9ba31e2b-fa3e-4b9d-8ca6-3bfe7fcb4d5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtendedMaturityAndInterestRateReductionMember_16a05d9d-c883-4dee-bd1c-bf6dd83367ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExtendedMaturityAndInterestRateReductionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_b0cf7b11-3c21-40e4-9b9e-52e43aca1fed" xlink:to="loc_us-gaap_ExtendedMaturityAndInterestRateReductionMember_16a05d9d-c883-4dee-bd1c-bf6dd83367ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_26bc9877-eae9-43e0-8837-2240c6791f6a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a12c27c-65b6-4ac7-b0f1-a31762035679" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_26bc9877-eae9-43e0-8837-2240c6791f6a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_26bc9877-eae9-43e0-8837-2240c6791f6a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_26bc9877-eae9-43e0-8837-2240c6791f6a" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_26bc9877-eae9-43e0-8837-2240c6791f6a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_6682862c-63dd-461c-b2cf-5d6e729d1a9c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_26bc9877-eae9-43e0-8837-2240c6791f6a" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_6682862c-63dd-461c-b2cf-5d6e729d1a9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPortfolioSegmentMember_03a65bc7-f5ee-4da3-98b8-830bea7b8997" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_6682862c-63dd-461c-b2cf-5d6e729d1a9c" xlink:to="loc_us-gaap_CommercialPortfolioSegmentMember_03a65bc7-f5ee-4da3-98b8-830bea7b8997" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_f60cc273-cd31-493d-9584-c6a850f0edf1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_7a12c27c-65b6-4ac7-b0f1-a31762035679" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_f60cc273-cd31-493d-9584-c6a850f0edf1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_f60cc273-cd31-493d-9584-c6a850f0edf1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_f60cc273-cd31-493d-9584-c6a850f0edf1" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_f60cc273-cd31-493d-9584-c6a850f0edf1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fe87334d-8baf-439a-af8f-8bc0e28acdad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_f60cc273-cd31-493d-9584-c6a850f0edf1" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fe87334d-8baf-439a-af8f-8bc0e28acdad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EquipmentFinancingMember_ce5364b5-840f-49fe-bc08-4656c51867f8" xlink:href="ucbi-20230331.xsd#ucbi_EquipmentFinancingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fe87334d-8baf-439a-af8f-8bc0e28acdad" xlink:to="loc_ucbi_EquipmentFinancingMember_ce5364b5-840f-49fe-bc08-4656c51867f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialAndIndustrialClassificationMember_06e44dc2-d97f-4549-8ab1-d10f4a30eef9" xlink:href="ucbi-20230331.xsd#ucbi_CommercialAndIndustrialClassificationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fe87334d-8baf-439a-af8f-8bc0e28acdad" xlink:to="loc_ucbi_CommercialAndIndustrialClassificationMember_06e44dc2-d97f-4549-8ab1-d10f4a30eef9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageAndManufacturedHousingMember_50929bd1-8bd9-479d-b1d3-a1d8396b399a" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageAndManufacturedHousingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_fe87334d-8baf-439a-af8f-8bc0e28acdad" xlink:to="loc_ucbi_ResidentialMortgageAndManufacturedHousingMember_50929bd1-8bd9-479d-b1d3-a1d8396b399a" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesLoansHeldforInvestmentSoldDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#LoansandLeasesandAllowanceforCreditLossesLoansHeldforInvestmentSoldDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesLoansHeldforInvestmentSoldDetails" xlink:type="extended" id="i8b20b5ac5d6541c18f33d3b208134b44_LoansandLeasesandAllowanceforCreditLossesLoansHeldforInvestmentSoldDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_f4b45b2c-b2b0-4352-8a7c-b058bfc56334" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableSignificantSales_b78398de-078b-41ec-82e2-b12956cee5a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableSignificantSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_f4b45b2c-b2b0-4352-8a7c-b058bfc56334" xlink:to="loc_us-gaap_FinancingReceivableSignificantSales_b78398de-078b-41ec-82e2-b12956cee5a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_cd1f9b9f-ab93-4f8a-a5cd-a15e2a3760f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_f4b45b2c-b2b0-4352-8a7c-b058bfc56334" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_cd1f9b9f-ab93-4f8a-a5cd-a15e2a3760f1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_9e81d9d5-a5a8-4f02-9aa4-f5305a23dedb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_cd1f9b9f-ab93-4f8a-a5cd-a15e2a3760f1" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_9e81d9d5-a5a8-4f02-9aa4-f5305a23dedb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_9e81d9d5-a5a8-4f02-9aa4-f5305a23dedb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_9e81d9d5-a5a8-4f02-9aa4-f5305a23dedb" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_9e81d9d5-a5a8-4f02-9aa4-f5305a23dedb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_8f751f3e-677e-4ecc-9f8b-b34e08490957" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_9e81d9d5-a5a8-4f02-9aa4-f5305a23dedb" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_8f751f3e-677e-4ecc-9f8b-b34e08490957" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_SBAUSDAGuaranteedLoansMember_980fd986-1e0a-420e-b45e-faad3e4f279c" xlink:href="ucbi-20230331.xsd#ucbi_SBAUSDAGuaranteedLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_8f751f3e-677e-4ecc-9f8b-b34e08490957" xlink:to="loc_ucbi_SBAUSDAGuaranteedLoansMember_980fd986-1e0a-420e-b45e-faad3e4f279c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EquipmentFinancingMember_b0afeb2c-d7d9-4b64-bb78-520deaed8d56" xlink:href="ucbi-20230331.xsd#ucbi_EquipmentFinancingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_8f751f3e-677e-4ecc-9f8b-b34e08490957" xlink:to="loc_ucbi_EquipmentFinancingMember_b0afeb2c-d7d9-4b64-bb78-520deaed8d56" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesLoansbyAgingCategoryandAccrualStatusDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#LoansandLeasesandAllowanceforCreditLossesLoansbyAgingCategoryandAccrualStatusDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesLoansbyAgingCategoryandAccrualStatusDetails" xlink:type="extended" id="i0e356903ba9c4c74b102c33ed99338b1_LoansandLeasesandAllowanceforCreditLossesLoansbyAgingCategoryandAccrualStatusDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_c9a74872-9b03-47af-8158-289854a7bd4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_9f226382-6431-4760-9194-6361bdc2d199" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_c9a74872-9b03-47af-8158-289854a7bd4e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_9f226382-6431-4760-9194-6361bdc2d199" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing_673b2d35-e6c1-47e8-ba9b-c4d0798d28d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_c9a74872-9b03-47af-8158-289854a7bd4e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterest90DaysOrMorePastDueStillAccruing_673b2d35-e6c1-47e8-ba9b-c4d0798d28d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual_8e9667b5-24ef-498b-9d84-9bf76d316480" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_c9a74872-9b03-47af-8158-289854a7bd4e" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual_8e9667b5-24ef-498b-9d84-9bf76d316480" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f4c2fffe-68a6-4ba7-ac3f-52fe70684d27" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_c9a74872-9b03-47af-8158-289854a7bd4e" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f4c2fffe-68a6-4ba7-ac3f-52fe70684d27" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_126bdd38-dc86-45dc-919e-6840cca9b0ce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f4c2fffe-68a6-4ba7-ac3f-52fe70684d27" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_126bdd38-dc86-45dc-919e-6840cca9b0ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_126bdd38-dc86-45dc-919e-6840cca9b0ce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_126bdd38-dc86-45dc-919e-6840cca9b0ce" xlink:to="loc_us-gaap_ReceivableTypeDomain_126bdd38-dc86-45dc-919e-6840cca9b0ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_52663513-9250-4b19-a13c-3b319b5f57f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_126bdd38-dc86-45dc-919e-6840cca9b0ce" xlink:to="loc_us-gaap_ReceivableTypeDomain_52663513-9250-4b19-a13c-3b319b5f57f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableMember_e74f76ab-58df-420f-8925-9366e1251a5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoansReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_52663513-9250-4b19-a13c-3b319b5f57f8" xlink:to="loc_us-gaap_LoansReceivableMember_e74f76ab-58df-420f-8925-9366e1251a5a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_237027d4-ccac-4d87-a625-5b6334a5a6e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f4c2fffe-68a6-4ba7-ac3f-52fe70684d27" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_237027d4-ccac-4d87-a625-5b6334a5a6e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_237027d4-ccac-4d87-a625-5b6334a5a6e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_237027d4-ccac-4d87-a625-5b6334a5a6e4" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_237027d4-ccac-4d87-a625-5b6334a5a6e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_c7fc8fa2-814d-4e34-a793-4b090c7b2443" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_237027d4-ccac-4d87-a625-5b6334a5a6e4" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_c7fc8fa2-814d-4e34-a793-4b090c7b2443" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPortfolioSegmentMember_7699d2e0-4e4f-4229-abb9-953b0dbc876f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_c7fc8fa2-814d-4e34-a793-4b090c7b2443" xlink:to="loc_us-gaap_CommercialPortfolioSegmentMember_7699d2e0-4e4f-4229-abb9-953b0dbc876f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_c541d13b-2de5-46a8-9253-2b36b9007317" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_c7fc8fa2-814d-4e34-a793-4b090c7b2443" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_c541d13b-2de5-46a8-9253-2b36b9007317" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_64b8a565-9600-4218-b2a4-20392dfc959d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_c7fc8fa2-814d-4e34-a793-4b090c7b2443" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_64b8a565-9600-4218-b2a4-20392dfc959d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_330d005f-0f7c-47f3-9bdb-66fa1fa358ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f4c2fffe-68a6-4ba7-ac3f-52fe70684d27" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_330d005f-0f7c-47f3-9bdb-66fa1fa358ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_330d005f-0f7c-47f3-9bdb-66fa1fa358ab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_330d005f-0f7c-47f3-9bdb-66fa1fa358ab" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_330d005f-0f7c-47f3-9bdb-66fa1fa358ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_330d005f-0f7c-47f3-9bdb-66fa1fa358ab" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_3cab2d67-f2f3-4db3-87b5-8d3f37956db8" xlink:href="ucbi-20230331.xsd#ucbi_OwnerOccupiedCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:to="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_3cab2d67-f2f3-4db3-87b5-8d3f37956db8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_IncomeProducingCommercialRealEstateMember_a1bf21a1-30d9-4db3-b018-c3b977f2ba85" xlink:href="ucbi-20230331.xsd#ucbi_IncomeProducingCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:to="loc_ucbi_IncomeProducingCommercialRealEstateMember_a1bf21a1-30d9-4db3-b018-c3b977f2ba85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialAndIndustrialClassificationMember_834d18f7-21ae-4fa2-9f30-bcb7cd3dde37" xlink:href="ucbi-20230331.xsd#ucbi_CommercialAndIndustrialClassificationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:to="loc_ucbi_CommercialAndIndustrialClassificationMember_834d18f7-21ae-4fa2-9f30-bcb7cd3dde37" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionLoansMember_b368efd2-7621-4462-9898-e23612edea6f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:to="loc_us-gaap_ConstructionLoansMember_b368efd2-7621-4462-9898-e23612edea6f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EquipmentFinancingMember_2c354231-04a5-4911-813a-b006f396878a" xlink:href="ucbi-20230331.xsd#ucbi_EquipmentFinancingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:to="loc_ucbi_EquipmentFinancingMember_2c354231-04a5-4911-813a-b006f396878a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageMember_857b2f26-e896-48b0-9369-0bd863cab3b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialMortgageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:to="loc_us-gaap_ResidentialMortgageMember_857b2f26-e896-48b0-9369-0bd863cab3b0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HomeEquityMember_3b0b4414-b5f5-417b-81e2-a6cdf12b706e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HomeEquityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:to="loc_us-gaap_HomeEquityMember_3b0b4414-b5f5-417b-81e2-a6cdf12b706e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ManufacturedHousingLoanMember_7715f097-eddf-4c75-84a1-570932e46eb4" xlink:href="ucbi-20230331.xsd#ucbi_ManufacturedHousingLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_c4708209-8f5b-4b8a-8379-564f9d4dd612" xlink:to="loc_ucbi_ManufacturedHousingLoanMember_7715f097-eddf-4c75-84a1-570932e46eb4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_e005294a-2f74-4747-a960-54ccb77627fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablesPeriodPastDueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_f4c2fffe-68a6-4ba7-ac3f-52fe70684d27" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_e005294a-2f74-4747-a960-54ccb77627fd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_e005294a-2f74-4747-a960-54ccb77627fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_e005294a-2f74-4747-a960-54ccb77627fd" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_e005294a-2f74-4747-a960-54ccb77627fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6388ea7a-1830-4b5b-8c00-2f37918d251b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablesPeriodPastDueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueAxis_e005294a-2f74-4747-a960-54ccb77627fd" xlink:to="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6388ea7a-1830-4b5b-8c00-2f37918d251b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialAssetNotPastDueMember_1c3bdca4-ebee-495d-bbf2-c787517fb977" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialAssetNotPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6388ea7a-1830-4b5b-8c00-2f37918d251b" xlink:to="loc_us-gaap_FinancialAssetNotPastDueMember_1c3bdca4-ebee-495d-bbf2-c787517fb977" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivables30To59DaysPastDueMember_0f61b9e0-1104-4d6d-a427-f946bfd96791" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivables30To59DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6388ea7a-1830-4b5b-8c00-2f37918d251b" xlink:to="loc_us-gaap_FinancingReceivables30To59DaysPastDueMember_0f61b9e0-1104-4d6d-a427-f946bfd96791" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivables60To89DaysPastDueMember_34730294-f446-4937-a3db-a5ad23783f17" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivables60To89DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6388ea7a-1830-4b5b-8c00-2f37918d251b" xlink:to="loc_us-gaap_FinancingReceivables60To89DaysPastDueMember_34730294-f446-4937-a3db-a5ad23783f17" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_44884357-fb03-4fad-b8f6-a31901f2acfc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablesPeriodPastDueDomain_6388ea7a-1830-4b5b-8c00-2f37918d251b" xlink:to="loc_us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember_44884357-fb03-4fad-b8f6-a31901f2acfc" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesNonaccrualLoansbyLoanClassDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#LoansandLeasesandAllowanceforCreditLossesNonaccrualLoansbyLoanClassDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesNonaccrualLoansbyLoanClassDetails" xlink:type="extended" id="i8947c7cd6d824aa5b36a64dcaa4c232d_LoansandLeasesandAllowanceforCreditLossesNonaccrualLoansbyLoanClassDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_6d834682-a2c1-43c3-a72c-df1e93440f33" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonaccrualStatusAbstract_dad23ee6-ba34-4c59-8d83-12ddc698f64a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonaccrualStatusAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_6d834682-a2c1-43c3-a72c-df1e93440f33" xlink:to="loc_us-gaap_NonaccrualStatusAbstract_dad23ee6-ba34-4c59-8d83-12ddc698f64a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance_a65d9224-ede5-46ca-8afc-7b2480b47424" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonaccrualStatusAbstract_dad23ee6-ba34-4c59-8d83-12ddc698f64a" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrualNoAllowance_a65d9224-ede5-46ca-8afc-7b2480b47424" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FinancingReceivableExcludingAccruedInterestNonaccrualWithAllowance_c848170e-c3ae-420a-901a-c82e6413211f" xlink:href="ucbi-20230331.xsd#ucbi_FinancingReceivableExcludingAccruedInterestNonaccrualWithAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonaccrualStatusAbstract_dad23ee6-ba34-4c59-8d83-12ddc698f64a" xlink:to="loc_ucbi_FinancingReceivableExcludingAccruedInterestNonaccrualWithAllowance_c848170e-c3ae-420a-901a-c82e6413211f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual_1cae0b81-9387-492a-a7fa-f47991759348" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonaccrualStatusAbstract_dad23ee6-ba34-4c59-8d83-12ddc698f64a" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestNonaccrual_1cae0b81-9387-492a-a7fa-f47991759348" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_ede81e82-ab67-47bf-ab4c-74f7be178b98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFinancingReceivablesPastDueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems_6d834682-a2c1-43c3-a72c-df1e93440f33" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_ede81e82-ab67-47bf-ab4c-74f7be178b98" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_c7fb52b2-6ccf-44e6-a2a7-e9790c939974" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_ede81e82-ab67-47bf-ab4c-74f7be178b98" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_c7fb52b2-6ccf-44e6-a2a7-e9790c939974" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_c7fb52b2-6ccf-44e6-a2a7-e9790c939974_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_c7fb52b2-6ccf-44e6-a2a7-e9790c939974" xlink:to="loc_us-gaap_ReceivableTypeDomain_c7fb52b2-6ccf-44e6-a2a7-e9790c939974_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_245c1a96-8ed5-41cf-afb4-2e62fd7d52b2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_c7fb52b2-6ccf-44e6-a2a7-e9790c939974" xlink:to="loc_us-gaap_ReceivableTypeDomain_245c1a96-8ed5-41cf-afb4-2e62fd7d52b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableMember_53996900-6a25-46d3-be54-d70bb7d9564e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoansReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_245c1a96-8ed5-41cf-afb4-2e62fd7d52b2" xlink:to="loc_us-gaap_LoansReceivableMember_53996900-6a25-46d3-be54-d70bb7d9564e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_fd62a360-d9b5-4cc9-b194-420028ad8292" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_ede81e82-ab67-47bf-ab4c-74f7be178b98" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_fd62a360-d9b5-4cc9-b194-420028ad8292" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fd62a360-d9b5-4cc9-b194-420028ad8292_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_fd62a360-d9b5-4cc9-b194-420028ad8292" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_fd62a360-d9b5-4cc9-b194-420028ad8292_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8225c8b3-2b74-4477-bd4b-60ade421c538" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_fd62a360-d9b5-4cc9-b194-420028ad8292" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8225c8b3-2b74-4477-bd4b-60ade421c538" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPortfolioSegmentMember_02748c73-5167-4f9a-8dfe-7b91c1b57405" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8225c8b3-2b74-4477-bd4b-60ade421c538" xlink:to="loc_us-gaap_CommercialPortfolioSegmentMember_02748c73-5167-4f9a-8dfe-7b91c1b57405" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_c42522f6-4e55-4641-8f01-0013413e190d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8225c8b3-2b74-4477-bd4b-60ade421c538" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_c42522f6-4e55-4641-8f01-0013413e190d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_50aaf524-6ed4-43f6-bb04-3e9c3e9c6951" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_8225c8b3-2b74-4477-bd4b-60ade421c538" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_50aaf524-6ed4-43f6-bb04-3e9c3e9c6951" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_756244e7-0f60-47f3-a7cb-2ec1665321cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivablesPastDueTable_ede81e82-ab67-47bf-ab4c-74f7be178b98" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_756244e7-0f60-47f3-a7cb-2ec1665321cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_756244e7-0f60-47f3-a7cb-2ec1665321cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_756244e7-0f60-47f3-a7cb-2ec1665321cf" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_756244e7-0f60-47f3-a7cb-2ec1665321cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_756244e7-0f60-47f3-a7cb-2ec1665321cf" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_6bcb9507-3ce9-47da-9e98-1daf887e1b44" xlink:href="ucbi-20230331.xsd#ucbi_OwnerOccupiedCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:to="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_6bcb9507-3ce9-47da-9e98-1daf887e1b44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_IncomeProducingCommercialRealEstateMember_22ee7011-d15e-46f3-abfb-788ff335a8a4" xlink:href="ucbi-20230331.xsd#ucbi_IncomeProducingCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:to="loc_ucbi_IncomeProducingCommercialRealEstateMember_22ee7011-d15e-46f3-abfb-788ff335a8a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialAndIndustrialClassificationMember_3058aca7-3346-47d8-a5ca-174ad5073fb1" xlink:href="ucbi-20230331.xsd#ucbi_CommercialAndIndustrialClassificationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:to="loc_ucbi_CommercialAndIndustrialClassificationMember_3058aca7-3346-47d8-a5ca-174ad5073fb1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionLoansMember_4c60c893-6400-4a40-b8f0-a8b03892cd56" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:to="loc_us-gaap_ConstructionLoansMember_4c60c893-6400-4a40-b8f0-a8b03892cd56" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EquipmentFinancingMember_f009a4c7-69fc-496f-b658-f423c8f9a065" xlink:href="ucbi-20230331.xsd#ucbi_EquipmentFinancingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:to="loc_ucbi_EquipmentFinancingMember_f009a4c7-69fc-496f-b658-f423c8f9a065" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageMember_a34245b2-61ff-49ab-ab89-e4cf66cf3744" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialMortgageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:to="loc_us-gaap_ResidentialMortgageMember_a34245b2-61ff-49ab-ab89-e4cf66cf3744" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HomeEquityMember_249e440a-846a-4be0-b8e7-6f4335bda9b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HomeEquityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:to="loc_us-gaap_HomeEquityMember_249e440a-846a-4be0-b8e7-6f4335bda9b7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ManufacturedHousingLoanMember_11e9d5b3-118c-4054-a9cb-a720e067b94d" xlink:href="ucbi-20230331.xsd#ucbi_ManufacturedHousingLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_dea962a2-063a-47a8-82a9-8d3af4a9b278" xlink:to="loc_ucbi_ManufacturedHousingLoanMember_11e9d5b3-118c-4054-a9cb-a720e067b94d" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesAmortizedCostofLoansbyRiskCategorybyVintageYearDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#LoansandLeasesandAllowanceforCreditLossesAmortizedCostofLoansbyRiskCategorybyVintageYearDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesAmortizedCostofLoansbyRiskCategorybyVintageYearDetails" xlink:type="extended" id="i30d275aa0e934fb28df841724ae4514a_LoansandLeasesandAllowanceforCreditLossesAmortizedCostofLoansbyRiskCategorybyVintageYearDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear_31daddab-bbcc-4ee6-a0f2-82af3d7802b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYear_31daddab-bbcc-4ee6-a0f2-82af3d7802b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear_009c171e-bcec-45b7-aeee-f61c88639b5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYear_009c171e-bcec-45b7-aeee-f61c88639b5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear_76a0ba37-e9e6-4765-a9b4-02f8f63fcc4c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYear_76a0ba37-e9e6-4765-a9b4-02f8f63fcc4c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear_1441d230-e74a-4ad9-ad05-cf4ceadb3354" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYear_1441d230-e74a-4ad9-ad05-cf4ceadb3354" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear_f7be6a2a-15ba-4c1a-9cde-786b0bfe6310" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYear_f7be6a2a-15ba-4c1a-9cde-786b0bfe6310" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear_94333db5-bb30-4b69-bec8-e5f3cd764ea0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYear_94333db5-bb30-4b69-bec8-e5f3cd764ea0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolving_ba0576f4-509c-4513-82d9-0d2186c51481" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolving"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolving_ba0576f4-509c-4513-82d9-0d2186c51481" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan_befbd838-8cdb-4348-a884-f42a50aa661e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoan_befbd838-8cdb-4348-a884-f42a50aa661e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_753e0d73-8482-44b6-bd73-6e9b75165fb1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss_753e0d73-8482-44b6-bd73-6e9b75165fb1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff_c5a22ca1-f140-49d4-a334-447521ac900a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff_c5a22ca1-f140-49d4-a334-447521ac900a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff_17b20a2b-824c-49d4-b41c-2c85746589de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff_17b20a2b-824c-49d4-b41c-2c85746589de" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff_fa7278e2-e345-4a0b-a17c-fe01fae1dc28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff_fa7278e2-e345-4a0b-a17c-fe01fae1dc28" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff_0e5fae07-8a4a-40b9-86d4-12a3e42685f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff_0e5fae07-8a4a-40b9-86d4-12a3e42685f9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff_82a2bcce-717d-468b-9cb9-f6cd2c783250" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff_82a2bcce-717d-468b-9cb9-f6cd2c783250" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff_ec2d3aea-5be5-4c55-b607-9462e48b4e4f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff_ec2d3aea-5be5-4c55-b607-9462e48b4e4f" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff_d5f1532c-4319-4033-9159-4e6c843fa933" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingWriteoff_d5f1532c-4319-4033-9159-4e6c843fa933" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff_54220941-f507-4a25-9135-1f50dc5aa30f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestRevolvingConvertedToTermLoanWriteoff_54220941-f507-4a25-9135-1f50dc5aa30f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_2af79694-dec6-4b96-a0da-d7ae5dde2545" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_2af79694-dec6-4b96-a0da-d7ae5dde2545" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_b2e10fa7-0618-4dc5-8edc-af9c8b102f2d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentLineItems_ae24e70b-3173-420f-bbe2-6cfe0e14b5de" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_b2e10fa7-0618-4dc5-8edc-af9c8b102f2d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_2b8ec9f3-4f90-49a9-a557-977fdbc1f208" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_b2e10fa7-0618-4dc5-8edc-af9c8b102f2d" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_2b8ec9f3-4f90-49a9-a557-977fdbc1f208" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2b8ec9f3-4f90-49a9-a557-977fdbc1f208_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_2b8ec9f3-4f90-49a9-a557-977fdbc1f208" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_2b8ec9f3-4f90-49a9-a557-977fdbc1f208_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0ac8b521-7568-4278-9ded-e7fe42a02f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_2b8ec9f3-4f90-49a9-a557-977fdbc1f208" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0ac8b521-7568-4278-9ded-e7fe42a02f9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPortfolioSegmentMember_ab47de83-4c65-4864-b2f2-131647e9f255" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0ac8b521-7568-4278-9ded-e7fe42a02f9a" xlink:to="loc_us-gaap_CommercialPortfolioSegmentMember_ab47de83-4c65-4864-b2f2-131647e9f255" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_44c2b927-2957-434a-9393-c286522c234b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0ac8b521-7568-4278-9ded-e7fe42a02f9a" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_44c2b927-2957-434a-9393-c286522c234b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_0c9f4604-780e-4500-979d-55fc107be1a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0ac8b521-7568-4278-9ded-e7fe42a02f9a" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_0c9f4604-780e-4500-979d-55fc107be1a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_2a3ac839-66b9-4a2f-95de-8b1803fac308" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_b2e10fa7-0618-4dc5-8edc-af9c8b102f2d" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_2a3ac839-66b9-4a2f-95de-8b1803fac308" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_2a3ac839-66b9-4a2f-95de-8b1803fac308_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_2a3ac839-66b9-4a2f-95de-8b1803fac308" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_2a3ac839-66b9-4a2f-95de-8b1803fac308_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_2a3ac839-66b9-4a2f-95de-8b1803fac308" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_15602da3-aa0e-432a-8e88-0067e9c887f2" xlink:href="ucbi-20230331.xsd#ucbi_OwnerOccupiedCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:to="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_15602da3-aa0e-432a-8e88-0067e9c887f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_IncomeProducingCommercialRealEstateMember_d57849aa-c4ff-41fc-87da-fa77536e7653" xlink:href="ucbi-20230331.xsd#ucbi_IncomeProducingCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:to="loc_ucbi_IncomeProducingCommercialRealEstateMember_d57849aa-c4ff-41fc-87da-fa77536e7653" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialAndIndustrialClassificationMember_287094b5-beac-4e4e-a6be-e545a7f6f45b" xlink:href="ucbi-20230331.xsd#ucbi_CommercialAndIndustrialClassificationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:to="loc_ucbi_CommercialAndIndustrialClassificationMember_287094b5-beac-4e4e-a6be-e545a7f6f45b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionLoansMember_9467a069-d49f-4122-ab37-504398e2cbaa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:to="loc_us-gaap_ConstructionLoansMember_9467a069-d49f-4122-ab37-504398e2cbaa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EquipmentFinancingMember_2a304d17-959b-44f6-99a9-d6c04c09959c" xlink:href="ucbi-20230331.xsd#ucbi_EquipmentFinancingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:to="loc_ucbi_EquipmentFinancingMember_2a304d17-959b-44f6-99a9-d6c04c09959c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageMember_462aa2c6-ce96-465a-a51b-b62de5f8f45b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialMortgageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:to="loc_us-gaap_ResidentialMortgageMember_462aa2c6-ce96-465a-a51b-b62de5f8f45b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HomeEquityMember_144ab678-7abc-451d-9d99-0f682ee4e03c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HomeEquityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:to="loc_us-gaap_HomeEquityMember_144ab678-7abc-451d-9d99-0f682ee4e03c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ManufacturedHousingLoanMember_5394f115-9056-415b-a400-c7f87477382c" xlink:href="ucbi-20230331.xsd#ucbi_ManufacturedHousingLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_255cd41c-6ad3-4984-9513-1007ad81b8f3" xlink:to="loc_ucbi_ManufacturedHousingLoanMember_5394f115-9056-415b-a400-c7f87477382c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentAxis_b86772a7-cf50-409d-a738-6f0851900804" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InternalCreditAssessmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableRecordedInvestmentCreditQualityIndicatorTable_b2e10fa7-0618-4dc5-8edc-af9c8b102f2d" xlink:to="loc_us-gaap_InternalCreditAssessmentAxis_b86772a7-cf50-409d-a738-6f0851900804" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentDomain_b86772a7-cf50-409d-a738-6f0851900804_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InternalCreditAssessmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InternalCreditAssessmentAxis_b86772a7-cf50-409d-a738-6f0851900804" xlink:to="loc_us-gaap_InternalCreditAssessmentDomain_b86772a7-cf50-409d-a738-6f0851900804_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalCreditAssessmentDomain_922156d0-3a44-4178-8bbf-11384715a886" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InternalCreditAssessmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InternalCreditAssessmentAxis_b86772a7-cf50-409d-a738-6f0851900804" xlink:to="loc_us-gaap_InternalCreditAssessmentDomain_922156d0-3a44-4178-8bbf-11384715a886" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PassMember_bc093b74-ed09-495d-852c-6fbd3a22be4a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PassMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_922156d0-3a44-4178-8bbf-11384715a886" xlink:to="loc_us-gaap_PassMember_bc093b74-ed09-495d-852c-6fbd3a22be4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SpecialMentionMember_b1f87cbb-806c-4a0c-9247-fdef684f446d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SpecialMentionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_922156d0-3a44-4178-8bbf-11384715a886" xlink:to="loc_us-gaap_SpecialMentionMember_b1f87cbb-806c-4a0c-9247-fdef684f446d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubstandardMember_64066848-7ec5-4482-8597-70992ff16086" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubstandardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_922156d0-3a44-4178-8bbf-11384715a886" xlink:to="loc_us-gaap_SubstandardMember_64066848-7ec5-4482-8597-70992ff16086" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DoubtfulMember_33718ed9-d425-4364-8e13-200c71980a9e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DoubtfulMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InternalCreditAssessmentDomain_922156d0-3a44-4178-8bbf-11384715a886" xlink:to="loc_us-gaap_DoubtfulMember_33718ed9-d425-4364-8e13-200c71980a9e" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesModificationstoBorrowersExperiencingFinancialDifficultyDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#LoansandLeasesandAllowanceforCreditLossesModificationstoBorrowersExperiencingFinancialDifficultyDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesModificationstoBorrowersExperiencingFinancialDifficultyDetails" xlink:type="extended" id="ic80a35e45db141c5aef4001cf31e3d29_LoansandLeasesandAllowanceforCreditLossesModificationstoBorrowersExperiencingFinancialDifficultyDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableModificationsLineItems_e6ca8f6d-31ed-42bb-aa4c-7614aece2d90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableModificationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod_90ee20e0-fb76-4597-9f2e-3bfd1b0fcc3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_e6ca8f6d-31ed-42bb-aa4c-7614aece2d90" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod_90ee20e0-fb76-4597-9f2e-3bfd1b0fcc3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent_e1607f1a-2e77-4cca-852c-aa170970e590" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_e6ca8f6d-31ed-42bb-aa4c-7614aece2d90" xlink:to="loc_us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent_e1607f1a-2e77-4cca-852c-aa170970e590" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_d0867104-90cd-4548-ab5e-006e40dda57d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableModificationsLineItems_e6ca8f6d-31ed-42bb-aa4c-7614aece2d90" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_d0867104-90cd-4548-ab5e-006e40dda57d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_4521701d-5cb0-4a9f-a252-1520be277c8b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_d0867104-90cd-4548-ab5e-006e40dda57d" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_4521701d-5cb0-4a9f-a252-1520be277c8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_4521701d-5cb0-4a9f-a252-1520be277c8b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_4521701d-5cb0-4a9f-a252-1520be277c8b" xlink:to="loc_us-gaap_ReceivableTypeDomain_4521701d-5cb0-4a9f-a252-1520be277c8b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_f662fd2f-cd1b-4c55-b27d-46041147743d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_4521701d-5cb0-4a9f-a252-1520be277c8b" xlink:to="loc_us-gaap_ReceivableTypeDomain_f662fd2f-cd1b-4c55-b27d-46041147743d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableMember_10966e27-5bc8-412d-abdd-c292cde3467b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoansReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_f662fd2f-cd1b-4c55-b27d-46041147743d" xlink:to="loc_us-gaap_LoansReceivableMember_10966e27-5bc8-412d-abdd-c292cde3467b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_5cd83858-dba9-4021-8841-e1e85ad375af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_d0867104-90cd-4548-ab5e-006e40dda57d" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_5cd83858-dba9-4021-8841-e1e85ad375af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5cd83858-dba9-4021-8841-e1e85ad375af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_5cd83858-dba9-4021-8841-e1e85ad375af" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_5cd83858-dba9-4021-8841-e1e85ad375af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0656d66e-0180-468d-93c7-3dde1f3b6e17" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_5cd83858-dba9-4021-8841-e1e85ad375af" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0656d66e-0180-468d-93c7-3dde1f3b6e17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPortfolioSegmentMember_ead17c70-b077-4e17-9fc2-97483c49fa30" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0656d66e-0180-468d-93c7-3dde1f3b6e17" xlink:to="loc_us-gaap_CommercialPortfolioSegmentMember_ead17c70-b077-4e17-9fc2-97483c49fa30" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_61a71483-1f3e-4d1f-8475-8b57f18a8934" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_0656d66e-0180-468d-93c7-3dde1f3b6e17" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_61a71483-1f3e-4d1f-8475-8b57f18a8934" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_da5781ff-9489-4f14-a9eb-eb7231f5f4b3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_d0867104-90cd-4548-ab5e-006e40dda57d" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_da5781ff-9489-4f14-a9eb-eb7231f5f4b3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_da5781ff-9489-4f14-a9eb-eb7231f5f4b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_da5781ff-9489-4f14-a9eb-eb7231f5f4b3" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_da5781ff-9489-4f14-a9eb-eb7231f5f4b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_01696187-ce58-47a2-bb47-f91d0ae8903b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_da5781ff-9489-4f14-a9eb-eb7231f5f4b3" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_01696187-ce58-47a2-bb47-f91d0ae8903b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialAndIndustrialClassificationMember_b1f0d8c7-9d33-4eb4-beb9-8165d5a4b9a7" xlink:href="ucbi-20230331.xsd#ucbi_CommercialAndIndustrialClassificationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_01696187-ce58-47a2-bb47-f91d0ae8903b" xlink:to="loc_ucbi_CommercialAndIndustrialClassificationMember_b1f0d8c7-9d33-4eb4-beb9-8165d5a4b9a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EquipmentFinancingMember_0276a0c7-78bd-41db-836d-2af5c8877e22" xlink:href="ucbi-20230331.xsd#ucbi_EquipmentFinancingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_01696187-ce58-47a2-bb47-f91d0ae8903b" xlink:to="loc_ucbi_EquipmentFinancingMember_0276a0c7-78bd-41db-836d-2af5c8877e22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageMember_1ba14f0a-8c63-4b41-aad6-a0e3fe43f209" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialMortgageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_01696187-ce58-47a2-bb47-f91d0ae8903b" xlink:to="loc_us-gaap_ResidentialMortgageMember_1ba14f0a-8c63-4b41-aad6-a0e3fe43f209" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ManufacturedHousingLoanMember_51ae1f05-ebcb-465a-9d46-18f484e2122b" xlink:href="ucbi-20230331.xsd#ucbi_ManufacturedHousingLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_01696187-ce58-47a2-bb47-f91d0ae8903b" xlink:to="loc_ucbi_ManufacturedHousingLoanMember_51ae1f05-ebcb-465a-9d46-18f484e2122b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationAxis_cda5f908-2a51-4a0f-944c-2727b28df76f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoanRestructuringModificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableTroubledDebtRestructuringsTable_d0867104-90cd-4548-ab5e-006e40dda57d" xlink:to="loc_us-gaap_LoanRestructuringModificationAxis_cda5f908-2a51-4a0f-944c-2727b28df76f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationDomain_cda5f908-2a51-4a0f-944c-2727b28df76f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoanRestructuringModificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LoanRestructuringModificationAxis_cda5f908-2a51-4a0f-944c-2727b28df76f" xlink:to="loc_us-gaap_LoanRestructuringModificationDomain_cda5f908-2a51-4a0f-944c-2727b28df76f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoanRestructuringModificationDomain_4d229446-972a-43e2-9923-d66795ec2355" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoanRestructuringModificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LoanRestructuringModificationAxis_cda5f908-2a51-4a0f-944c-2727b28df76f" xlink:to="loc_us-gaap_LoanRestructuringModificationDomain_4d229446-972a-43e2-9923-d66795ec2355" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtendedMaturityMember_7e98237a-da4e-4652-89a6-d3daa352e396" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExtendedMaturityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_4d229446-972a-43e2-9923-d66795ec2355" xlink:to="loc_us-gaap_ExtendedMaturityMember_7e98237a-da4e-4652-89a6-d3daa352e396" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentDeferralMember_10fadd22-fe74-438c-bffc-803a59e4a41b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentDeferralMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_4d229446-972a-43e2-9923-d66795ec2355" xlink:to="loc_us-gaap_PaymentDeferralMember_10fadd22-fe74-438c-bffc-803a59e4a41b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtendedMaturityAndInterestRateReductionMember_e0f08e09-80da-4c21-a0e5-31fa4a0f9aba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ExtendedMaturityAndInterestRateReductionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LoanRestructuringModificationDomain_4d229446-972a-43e2-9923-d66795ec2355" xlink:to="loc_us-gaap_ExtendedMaturityAndInterestRateReductionMember_e0f08e09-80da-4c21-a0e5-31fa4a0f9aba" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesBalanceandActivityintheACLbyPortfolioSegmentDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#LoansandLeasesandAllowanceforCreditLossesBalanceandActivityintheACLbyPortfolioSegmentDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/LoansandLeasesandAllowanceforCreditLossesBalanceandActivityintheACLbyPortfolioSegmentDetails" xlink:type="extended" id="i30c15042e9bd4971b0c7490a0a53466d_LoansandLeasesandAllowanceforCreditLossesBalanceandActivityintheACLbyPortfolioSegmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_0470fd3f-bc22-4493-857f-0bd91753dcae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_0470fd3f-bc22-4493-857f-0bd91753dcae" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_82fb6ddf-1f1d-4df0-ab34-206e04175768" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_82fb6ddf-1f1d-4df0-ab34-206e04175768" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestPurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate_6730ef3b-6926-4d1a-a100-494515ea793f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestPurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestPurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate_6730ef3b-6926-4d1a-a100-494515ea793f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_7e7c70c5-3cfa-430a-942a-3f61bfd679e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff_7e7c70c5-3cfa-430a-942a-3f61bfd679e0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery_4932bde7-f5b9-4057-bbce-c40652802e78" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery_4932bde7-f5b9-4057-bbce-c40652802e78" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal_a53fbd28-43bd-4302-8867-5e8a479fba24" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal_a53fbd28-43bd-4302-8867-5e8a479fba24" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest_b17d38b4-135f-4d49-a47c-fbca9f6dd296" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffBalanceSheetCreditLossLiability_824ab288-692b-4bf5-9544-0a90315cdbaf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OffBalanceSheetCreditLossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_us-gaap_OffBalanceSheetCreditLossLiability_824ab288-692b-4bf5-9544-0a90315cdbaf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal_e50c2981-bcbd-44e8-be18-f45b8226b7e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_us-gaap_OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal_e50c2981-bcbd-44e8-be18-f45b8226b7e8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OffBalanceSheetCreditLossLiability_fe1a3c2b-4919-4600-9ddb-650767c8df34" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OffBalanceSheetCreditLossLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterestAndOffBalanceSheetCreditLossLiability_da906228-2989-463e-ad8f-920313ce1c0d" xlink:href="ucbi-20230331.xsd#ucbi_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterestAndOffBalanceSheetCreditLossLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_ucbi_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterestAndOffBalanceSheetCreditLossLiability_da906228-2989-463e-ad8f-920313ce1c0d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityPurchasedWithCreditDeteriorationIncrease_ea916b63-96bc-4ea5-b737-4cdd3443f43b" xlink:href="ucbi-20230331.xsd#ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityPurchasedWithCreditDeteriorationIncrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityPurchasedWithCreditDeteriorationIncrease_ea916b63-96bc-4ea5-b737-4cdd3443f43b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityWriteoff_6f34bb78-3c48-401b-badd-b283f9e4e345" xlink:href="ucbi-20230331.xsd#ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityWriteoff"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityWriteoff_6f34bb78-3c48-401b-badd-b283f9e4e345" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityRecovery_263abca6-aafa-40bd-9cc3-3cf2e81d8804" xlink:href="ucbi-20230331.xsd#ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityRecovery"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_ucbi_FinancingReceivableAllowanceForCreditLossAndOffBalanceSheetCreditLossLiabilityRecovery_263abca6-aafa-40bd-9cc3-3cf2e81d8804" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_4b8ab1bf-372a-43f0-b529-274b17015cf4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForLoanLeaseAndOtherLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesRollForward_0c76df01-572d-413a-80ce-ee9e9aea462a" xlink:to="loc_us-gaap_ProvisionForLoanLeaseAndOtherLosses_4b8ab1bf-372a-43f0-b529-274b17015cf4" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterestAndOffBalanceSheetCreditLossLiability_48644742-54e4-4370-a907-7fd2b2fd27cd" xlink:href="ucbi-20230331.xsd#ucbi_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterestAndOffBalanceSheetCreditLossLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_08b1a5e0-980f-45c5-ab1a-03adc08bbba8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems_0470fd3f-bc22-4493-857f-0bd91753dcae" xlink:to="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_08b1a5e0-980f-45c5-ab1a-03adc08bbba8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_f2c4db8e-e1f4-4a18-9fdc-78b79bb90909" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_08b1a5e0-980f-45c5-ab1a-03adc08bbba8" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_f2c4db8e-e1f4-4a18-9fdc-78b79bb90909" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_f2c4db8e-e1f4-4a18-9fdc-78b79bb90909_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_f2c4db8e-e1f4-4a18-9fdc-78b79bb90909" xlink:to="loc_us-gaap_ReceivableTypeDomain_f2c4db8e-e1f4-4a18-9fdc-78b79bb90909_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_5790f63c-538c-4acb-a7bb-857db958d063" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_f2c4db8e-e1f4-4a18-9fdc-78b79bb90909" xlink:to="loc_us-gaap_ReceivableTypeDomain_5790f63c-538c-4acb-a7bb-857db958d063" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableMember_b8bf1f67-4024-4a56-8942-3d2b5b19f1a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoansReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_5790f63c-538c-4acb-a7bb-857db958d063" xlink:to="loc_us-gaap_LoansReceivableMember_b8bf1f67-4024-4a56-8942-3d2b5b19f1a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_13fa0695-92a0-4f13-bf7f-4aa2f3a196eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_08b1a5e0-980f-45c5-ab1a-03adc08bbba8" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_13fa0695-92a0-4f13-bf7f-4aa2f3a196eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_13fa0695-92a0-4f13-bf7f-4aa2f3a196eb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_13fa0695-92a0-4f13-bf7f-4aa2f3a196eb" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_13fa0695-92a0-4f13-bf7f-4aa2f3a196eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_4a1698bb-cbe5-4eea-82ca-7e642197c2ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivablePortfolioSegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentAxis_13fa0695-92a0-4f13-bf7f-4aa2f3a196eb" xlink:to="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_4a1698bb-cbe5-4eea-82ca-7e642197c2ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPortfolioSegmentMember_3867f4ac-6375-4e39-b73c-bafe731b05d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_4a1698bb-cbe5-4eea-82ca-7e642197c2ff" xlink:to="loc_us-gaap_CommercialPortfolioSegmentMember_3867f4ac-6375-4e39-b73c-bafe731b05d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialPortfolioSegmentMember_2908751a-04ca-4514-a911-5318a7499484" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_4a1698bb-cbe5-4eea-82ca-7e642197c2ff" xlink:to="loc_us-gaap_ResidentialPortfolioSegmentMember_2908751a-04ca-4514-a911-5318a7499484" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsumerPortfolioSegmentMember_7d98aac3-4ad9-4463-94a8-df5c7695e775" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConsumerPortfolioSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivablePortfolioSegmentDomain_4a1698bb-cbe5-4eea-82ca-7e642197c2ff" xlink:to="loc_us-gaap_ConsumerPortfolioSegmentMember_7d98aac3-4ad9-4463-94a8-df5c7695e775" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_7318f57a-aee6-4304-bc77-1406261a25ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFinancingReceivableAllowanceForCreditLossesTable_08b1a5e0-980f-45c5-ab1a-03adc08bbba8" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_7318f57a-aee6-4304-bc77-1406261a25ba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7318f57a-aee6-4304-bc77-1406261a25ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_7318f57a-aee6-4304-bc77-1406261a25ba" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_7318f57a-aee6-4304-bc77-1406261a25ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis_7318f57a-aee6-4304-bc77-1406261a25ba" xlink:to="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_aeff147b-1b60-4fee-9bc2-e69c598d589a" xlink:href="ucbi-20230331.xsd#ucbi_OwnerOccupiedCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:to="loc_ucbi_OwnerOccupiedCommercialRealEstateMember_aeff147b-1b60-4fee-9bc2-e69c598d589a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_IncomeProducingCommercialRealEstateMember_6e25d205-60ca-41ea-aed5-d5caf7952361" xlink:href="ucbi-20230331.xsd#ucbi_IncomeProducingCommercialRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:to="loc_ucbi_IncomeProducingCommercialRealEstateMember_6e25d205-60ca-41ea-aed5-d5caf7952361" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CommercialAndIndustrialClassificationMember_43a99c2a-589b-4c4e-a5e2-156403a2a618" xlink:href="ucbi-20230331.xsd#ucbi_CommercialAndIndustrialClassificationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:to="loc_ucbi_CommercialAndIndustrialClassificationMember_43a99c2a-589b-4c4e-a5e2-156403a2a618" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionLoansMember_950f61ec-ea18-4a1f-9d42-277217f619c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:to="loc_us-gaap_ConstructionLoansMember_950f61ec-ea18-4a1f-9d42-277217f619c0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EquipmentFinancingMember_ef139433-8f9c-4b64-9ecc-d951bcf35e48" xlink:href="ucbi-20230331.xsd#ucbi_EquipmentFinancingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:to="loc_ucbi_EquipmentFinancingMember_ef139433-8f9c-4b64-9ecc-d951bcf35e48" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageMember_d7563637-3ce7-4b6e-90a8-bff261079100" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialMortgageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:to="loc_us-gaap_ResidentialMortgageMember_d7563637-3ce7-4b6e-90a8-bff261079100" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HomeEquityMember_6a2da85a-e45a-477f-8f7a-787832d90c27" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HomeEquityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:to="loc_us-gaap_HomeEquityMember_6a2da85a-e45a-477f-8f7a-787832d90c27" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ManufacturedHousingLoanMember_cc547af9-baa9-443c-90c5-1d967fad9dc2" xlink:href="ucbi-20230331.xsd#ucbi_ManufacturedHousingLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancingReceivableRecordedInvestmentClassOfFinancingReceivableDomain_bebcf8a9-edba-4d80-86db-1a328b03d170" xlink:to="loc_ucbi_ManufacturedHousingLoanMember_cc547af9-baa9-443c-90c5-1d967fad9dc2" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/DerivativesandHedgingActivitiesFairValueofDerivativeFinancialInstrumentsDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#DerivativesandHedgingActivitiesFairValueofDerivativeFinancialInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/DerivativesandHedgingActivitiesFairValueofDerivativeFinancialInstrumentsDetails" xlink:type="extended" id="i27fa36ec212e484eaab76eebab88e6bb_DerivativesandHedgingActivitiesFairValueofDerivativeFinancialInstrumentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_e790024c-5c08-4c11-9b0a-fffdb583212a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_1a77d2ff-c226-4a63-afae-eb8591e892c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_e790024c-5c08-4c11-9b0a-fffdb583212a" xlink:to="loc_us-gaap_DerivativeNotionalAmount_1a77d2ff-c226-4a63-afae-eb8591e892c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_e790024c-5c08-4c11-9b0a-fffdb583212a" xlink:to="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeAssetAtFairValue_65eff157-d27b-4f91-aadb-9edc7123c4ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateCashFlowHedgeAssetAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeAssetAtFairValue_65eff157-d27b-4f91-aadb-9edc7123c4ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueHedgeAssetsAtFairValue_602a11d8-ceaf-40f4-8a3b-c5ac12d4bfcc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueHedgeAssetsAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:to="loc_us-gaap_FairValueHedgeAssetsAtFairValue_602a11d8-ceaf-40f4-8a3b-c5ac12d4bfcc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue_739fa890-db30-44d1-9c42-ed01512e11b2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue_739fa890-db30-44d1-9c42-ed01512e11b2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_d97f64b9-3377-4a2a-bb55-c171047d1a61" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:to="loc_us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_d97f64b9-3377-4a2a-bb55-c171047d1a61" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_d8c0ddcf-95a0-4701-b783-c167e5133259" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_d8c0ddcf-95a0-4701-b783-c167e5133259" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction_72161fd5-de6b-4eaa-9244-1bfd1548f92b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:to="loc_us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction_72161fd5-de6b-4eaa-9244-1bfd1548f92b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueOfCollateral_fcbd62dd-48cf-470c-90c0-4b6fd46cd4f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetFairValueOfCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:to="loc_us-gaap_DerivativeAssetFairValueOfCollateral_fcbd62dd-48cf-470c-90c0-4b6fd46cd4f4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_5cb3cf8e-13ad-4467-8d59-2068ac90cedb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeAssetsAbstract_20237303-a20f-438e-a713-0c897a50c849" xlink:to="loc_us-gaap_DerivativeAssetFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_5cb3cf8e-13ad-4467-8d59-2068ac90cedb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_e790024c-5c08-4c11-9b0a-fffdb583212a" xlink:to="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeLiabilityAtFairValue_232680df-7dd3-47dc-a1a6-741718bb4ed5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateCashFlowHedgeLiabilityAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeLiabilityAtFairValue_232680df-7dd3-47dc-a1a6-741718bb4ed5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueHedgeLiabilitiesAtFairValue_94eaf327-632c-48e2-84d5-a6d10ef2777c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueHedgeLiabilitiesAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:to="loc_us-gaap_FairValueHedgeLiabilitiesAtFairValue_94eaf327-632c-48e2-84d5-a6d10ef2777c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_58f36aa2-19c4-413e-ab7f-c77325e78ebc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_58f36aa2-19c4-413e-ab7f-c77325e78ebc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_68095d91-5f42-470e-bb04-b7f7cf871812" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:to="loc_us-gaap_InterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_68095d91-5f42-470e-bb04-b7f7cf871812" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_413d5d71-75ad-4393-a91c-a0ae61d87d33" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_413d5d71-75ad-4393-a91c-a0ae61d87d33" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction_194fc653-3086-4baf-a850-1e47927782a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:to="loc_us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction_194fc653-3086-4baf-a850-1e47927782a0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueOfCollateral_b0a78013-70e5-4f5d-ae92-437ec04735e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityFairValueOfCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueOfCollateral_b0a78013-70e5-4f5d-ae92-437ec04735e2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_b6088fec-2f6a-4c2f-8070-e197ba674dc7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilityFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLiabilitiesAbstract_b7ff0fa0-efdd-48d3-ad0d-e2e4858b9a89" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueOffsetAgainstCollateralNetOfNotSubjectToMasterNettingArrangementPolicyElection_b6088fec-2f6a-4c2f-8070-e197ba674dc7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_0132728f-8e2d-4ae3-a0a5-fe695a5cc7d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_e790024c-5c08-4c11-9b0a-fffdb583212a" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_0132728f-8e2d-4ae3-a0a5-fe695a5cc7d4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_690d90e7-e006-48a2-9906-03141c670c31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_0132728f-8e2d-4ae3-a0a5-fe695a5cc7d4" xlink:to="loc_us-gaap_HedgingDesignationAxis_690d90e7-e006-48a2-9906-03141c670c31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_690d90e7-e006-48a2-9906-03141c670c31_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_690d90e7-e006-48a2-9906-03141c670c31" xlink:to="loc_us-gaap_HedgingDesignationDomain_690d90e7-e006-48a2-9906-03141c670c31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_f09a6f14-d2c2-4ebc-8a76-543af8369857" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_690d90e7-e006-48a2-9906-03141c670c31" xlink:to="loc_us-gaap_HedgingDesignationDomain_f09a6f14-d2c2-4ebc-8a76-543af8369857" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_f25cfffe-ccc9-4de9-bbd2-0db8bb6f3ebc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_f09a6f14-d2c2-4ebc-8a76-543af8369857" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_f25cfffe-ccc9-4de9-bbd2-0db8bb6f3ebc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_6b43d98e-ea7d-47df-8377-064ee0695be1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_f09a6f14-d2c2-4ebc-8a76-543af8369857" xlink:to="loc_us-gaap_NondesignatedMember_6b43d98e-ea7d-47df-8377-064ee0695be1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_c345ed2f-8478-40cf-9bb9-6d069e4cfd3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_0132728f-8e2d-4ae3-a0a5-fe695a5cc7d4" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_c345ed2f-8478-40cf-9bb9-6d069e4cfd3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_c345ed2f-8478-40cf-9bb9-6d069e4cfd3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_c345ed2f-8478-40cf-9bb9-6d069e4cfd3c" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_c345ed2f-8478-40cf-9bb9-6d069e4cfd3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_0e5a1d6d-96fb-454e-8aaf-6ab5c0cbcef7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_c345ed2f-8478-40cf-9bb9-6d069e4cfd3c" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_0e5a1d6d-96fb-454e-8aaf-6ab5c0cbcef7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsAssetsMember_b201fe2e-c492-4455-a813-037ef690fb33" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFinancialInstrumentsAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_0e5a1d6d-96fb-454e-8aaf-6ab5c0cbcef7" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsAssetsMember_b201fe2e-c492-4455-a813-037ef690fb33" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_b57e559e-a905-4b22-9c58-85fd07b2397a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_0e5a1d6d-96fb-454e-8aaf-6ab5c0cbcef7" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_b57e559e-a905-4b22-9c58-85fd07b2397a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_9bb6fc05-9609-4493-be53-f4cd65fedbd5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_0132728f-8e2d-4ae3-a0a5-fe695a5cc7d4" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_9bb6fc05-9609-4493-be53-f4cd65fedbd5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_9bb6fc05-9609-4493-be53-f4cd65fedbd5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_9bb6fc05-9609-4493-be53-f4cd65fedbd5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_9bb6fc05-9609-4493-be53-f4cd65fedbd5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_9bb6fc05-9609-4493-be53-f4cd65fedbd5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_InterestRateContractSubordinatedDebtMember_7d4f0556-495c-4065-aeb8-e02c7acf944a" xlink:href="ucbi-20230331.xsd#ucbi_InterestRateContractSubordinatedDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_InterestRateContractSubordinatedDebtMember_7d4f0556-495c-4065-aeb8-e02c7acf944a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_TrustPreferredSecuritiesHedgeMember_ebcd7093-1412-44d6-913b-db8835636138" xlink:href="ucbi-20230331.xsd#ucbi_TrustPreferredSecuritiesHedgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_TrustPreferredSecuritiesHedgeMember_ebcd7093-1412-44d6-913b-db8835636138" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BrokeredCertificateOfDepositMember_3107fd4a-44b7-4276-a82b-51a3e63128cc" xlink:href="ucbi-20230331.xsd#ucbi_BrokeredCertificateOfDepositMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_BrokeredCertificateOfDepositMember_3107fd4a-44b7-4276-a82b-51a3e63128cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CustomerSwapPositionMember_dbc472e2-a875-430c-adb3-ca6cad404653" xlink:href="ucbi-20230331.xsd#ucbi_CustomerSwapPositionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_CustomerSwapPositionMember_dbc472e2-a875-430c-adb3-ca6cad404653" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DealerOffsetToCustomerSwapPositionMember_a8d6005b-d0f6-4ac0-a4aa-322a2a66cd2c" xlink:href="ucbi-20230331.xsd#ucbi_DealerOffsetToCustomerSwapPositionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_DealerOffsetToCustomerSwapPositionMember_a8d6005b-d0f6-4ac0-a4aa-322a2a66cd2c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_RiskParticipationsMember_510f5fb0-774d-4c09-ae29-26d47c4b97ab" xlink:href="ucbi-20230331.xsd#ucbi_RiskParticipationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_RiskParticipationsMember_510f5fb0-774d-4c09-ae29-26d47c4b97ab" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_MortgageBankingLoanCommitmentMember_474845b4-757a-4948-9d72-ff463b13ceb9" xlink:href="ucbi-20230331.xsd#ucbi_MortgageBankingLoanCommitmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_MortgageBankingLoanCommitmentMember_474845b4-757a-4948-9d72-ff463b13ceb9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_MortgageBankingForwardSalesCommitmentMember_3a8a11bb-7964-4b95-9f27-3cc35651e702" xlink:href="ucbi-20230331.xsd#ucbi_MortgageBankingForwardSalesCommitmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_MortgageBankingForwardSalesCommitmentMember_3a8a11bb-7964-4b95-9f27-3cc35651e702" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BifurcatedEmbeddedDerivativeMember_92202fea-1e02-4a05-848c-a7508d81139f" xlink:href="ucbi-20230331.xsd#ucbi_BifurcatedEmbeddedDerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_BifurcatedEmbeddedDerivativeMember_92202fea-1e02-4a05-848c-a7508d81139f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DealerOffsetsToBifurcatedEmbeddedDerivativesMember_beb699b2-6d60-41bc-ab18-fb0068bc4b30" xlink:href="ucbi-20230331.xsd#ucbi_DealerOffsetsToBifurcatedEmbeddedDerivativesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_deb9e958-61c6-4b9d-8d4c-44c3fdf36290" xlink:to="loc_ucbi_DealerOffsetsToBifurcatedEmbeddedDerivativesMember_beb699b2-6d60-41bc-ab18-fb0068bc4b30" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/DerivativesandHedgingActivitiesNarrativeDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#DerivativesandHedgingActivitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/DerivativesandHedgingActivitiesNarrativeDetails" xlink:type="extended" id="i7502d0b9a8a94c898412b25db2b5ea46_DerivativesandHedgingActivitiesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_f850e1be-f781-45d8-a693-5de7fbc618cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_c36a5dbe-0a39-4e6f-9c13-4b8be27d8207" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_f850e1be-f781-45d8-a693-5de7fbc618cc" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_c36a5dbe-0a39-4e6f-9c13-4b8be27d8207" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfInterestRateDerivativesHeld_9f0bb501-e3a1-4a35-ad1b-ac00eaf7947c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfInterestRateDerivativesHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_f850e1be-f781-45d8-a693-5de7fbc618cc" xlink:to="loc_us-gaap_NumberOfInterestRateDerivativesHeld_9f0bb501-e3a1-4a35-ad1b-ac00eaf7947c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_0011a9fd-5ba3-4b4e-82e9-ec80eae2710e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_f850e1be-f781-45d8-a693-5de7fbc618cc" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_0011a9fd-5ba3-4b4e-82e9-ec80eae2710e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_2179f48f-a8c0-462f-bf06-90e92f762e9e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_0011a9fd-5ba3-4b4e-82e9-ec80eae2710e" xlink:to="loc_us-gaap_HedgingDesignationAxis_2179f48f-a8c0-462f-bf06-90e92f762e9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_2179f48f-a8c0-462f-bf06-90e92f762e9e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_2179f48f-a8c0-462f-bf06-90e92f762e9e" xlink:to="loc_us-gaap_HedgingDesignationDomain_2179f48f-a8c0-462f-bf06-90e92f762e9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_ed4eef43-caf0-4d35-88ef-663ea3ba3640" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_2179f48f-a8c0-462f-bf06-90e92f762e9e" xlink:to="loc_us-gaap_HedgingDesignationDomain_ed4eef43-caf0-4d35-88ef-663ea3ba3640" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember_772738a7-4632-4e18-80ba-7b3ccadffe60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_ed4eef43-caf0-4d35-88ef-663ea3ba3640" xlink:to="loc_us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember_772738a7-4632-4e18-80ba-7b3ccadffe60" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_45a34e3a-bb71-4902-97d5-bff4db345cd1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_0011a9fd-5ba3-4b4e-82e9-ec80eae2710e" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_45a34e3a-bb71-4902-97d5-bff4db345cd1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_45a34e3a-bb71-4902-97d5-bff4db345cd1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_45a34e3a-bb71-4902-97d5-bff4db345cd1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_45a34e3a-bb71-4902-97d5-bff4db345cd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_c9bc8138-5676-4eea-a0cc-ed70db07809a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_45a34e3a-bb71-4902-97d5-bff4db345cd1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_c9bc8138-5676-4eea-a0cc-ed70db07809a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_62f0ad28-af94-4767-934a-623eeae59679" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_c9bc8138-5676-4eea-a0cc-ed70db07809a" xlink:to="loc_us-gaap_InterestRateSwapMember_62f0ad28-af94-4767-934a-623eeae59679" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/DerivativesandHedgingActivitiesEffectofDerivativesinHedgingRelationshipsDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#DerivativesandHedgingActivitiesEffectofDerivativesinHedgingRelationshipsDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/DerivativesandHedgingActivitiesEffectofDerivativesinHedgingRelationshipsDetails" xlink:type="extended" id="id6db94a69fb04c648eaeb2415a157398_DerivativesandHedgingActivitiesEffectofDerivativesinHedgingRelationshipsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_dc09c291-97c0-4f9b-9641-f0f933d8699a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_f3cf5d4f-e6a2-452d-9661-4770186f8f2b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_dc09c291-97c0-4f9b-9641-f0f933d8699a" xlink:to="loc_us-gaap_InterestExpense_f3cf5d4f-e6a2-452d-9661-4770186f8f2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract_4087ce9d-2543-40ea-a954-2114a82b6c81" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_dc09c291-97c0-4f9b-9641-f0f933d8699a" xlink:to="loc_us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract_4087ce9d-2543-40ea-a954-2114a82b6c81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_f404fda4-d11d-42dc-a250-7aa371aa6d2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnDerivativeInstrumentsNetPretax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract_4087ce9d-2543-40ea-a954-2114a82b6c81" xlink:to="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_f404fda4-d11d-42dc-a250-7aa371aa6d2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossFromComponentsExcludedFromAssessmentOfCashFlowHedgeEffectiveness_bc16e5d6-7071-48dd-8bc8-9f1a864cce88" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossFromComponentsExcludedFromAssessmentOfCashFlowHedgeEffectiveness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SummaryOfDerivativeInstrumentsImpactOnResultsOfOperationsAbstract_4087ce9d-2543-40ea-a954-2114a82b6c81" xlink:to="loc_us-gaap_LossFromComponentsExcludedFromAssessmentOfCashFlowHedgeEffectiveness_bc16e5d6-7071-48dd-8bc8-9f1a864cce88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_39582ae0-db26-48fc-b144-a12a2eb16b5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_dc09c291-97c0-4f9b-9641-f0f933d8699a" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_39582ae0-db26-48fc-b144-a12a2eb16b5c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_7b6ae083-49cf-49f6-b100-0f5dfa929b17" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_39582ae0-db26-48fc-b144-a12a2eb16b5c" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_7b6ae083-49cf-49f6-b100-0f5dfa929b17" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_7b6ae083-49cf-49f6-b100-0f5dfa929b17_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_7b6ae083-49cf-49f6-b100-0f5dfa929b17" xlink:to="loc_us-gaap_HedgingRelationshipDomain_7b6ae083-49cf-49f6-b100-0f5dfa929b17_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_586d8f2a-4c0b-4e62-b0f9-2aa71f638a03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_7b6ae083-49cf-49f6-b100-0f5dfa929b17" xlink:to="loc_us-gaap_HedgingRelationshipDomain_586d8f2a-4c0b-4e62-b0f9-2aa71f638a03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueHedgingMember_c6113de9-6dfd-4944-8394-0d2e5d89813f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_586d8f2a-4c0b-4e62-b0f9-2aa71f638a03" xlink:to="loc_us-gaap_FairValueHedgingMember_c6113de9-6dfd-4944-8394-0d2e5d89813f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_12d39d44-b864-498d-ab7f-5b922021596c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_586d8f2a-4c0b-4e62-b0f9-2aa71f638a03" xlink:to="loc_us-gaap_CashFlowHedgingMember_12d39d44-b864-498d-ab7f-5b922021596c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_57fb6087-1f3c-40d2-b60c-5f25e333ca5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_39582ae0-db26-48fc-b144-a12a2eb16b5c" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_57fb6087-1f3c-40d2-b60c-5f25e333ca5b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_57fb6087-1f3c-40d2-b60c-5f25e333ca5b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_57fb6087-1f3c-40d2-b60c-5f25e333ca5b" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_57fb6087-1f3c-40d2-b60c-5f25e333ca5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_bbb8cf22-1f18-45ce-a2fe-b4f02fcb7ffc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_57fb6087-1f3c-40d2-b60c-5f25e333ca5b" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_bbb8cf22-1f18-45ce-a2fe-b4f02fcb7ffc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseMember_4e44ea48-efa3-4d94-84f4-ffb1858993a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_bbb8cf22-1f18-45ce-a2fe-b4f02fcb7ffc" xlink:to="loc_us-gaap_InterestExpenseMember_4e44ea48-efa3-4d94-84f4-ffb1858993a7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/DerivativesandHedgingActivitiesGainsandLossesRecognizedinIncomeonDerivativesNotDesignatedasHedgingInstrumentsDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#DerivativesandHedgingActivitiesGainsandLossesRecognizedinIncomeonDerivativesNotDesignatedasHedgingInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/DerivativesandHedgingActivitiesGainsandLossesRecognizedinIncomeonDerivativesNotDesignatedasHedgingInstrumentsDetails" xlink:type="extended" id="i4a7c77dfe50e402088ab5d1b335a1a38_DerivativesandHedgingActivitiesGainsandLossesRecognizedinIncomeonDerivativesNotDesignatedasHedgingInstrumentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8883975f-d8cf-44a6-9de1-e3019715e449" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_3a0dd2df-beee-401a-9c2d-5a286824c4ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8883975f-d8cf-44a6-9de1-e3019715e449" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_3a0dd2df-beee-401a-9c2d-5a286824c4ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_0cb32926-6014-414c-a907-c8a3280bb5e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_8883975f-d8cf-44a6-9de1-e3019715e449" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_0cb32926-6014-414c-a907-c8a3280bb5e7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_ee068c59-68bd-4668-8904-3689f6db9e57" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_0cb32926-6014-414c-a907-c8a3280bb5e7" xlink:to="loc_us-gaap_HedgingDesignationAxis_ee068c59-68bd-4668-8904-3689f6db9e57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_ee068c59-68bd-4668-8904-3689f6db9e57_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_ee068c59-68bd-4668-8904-3689f6db9e57" xlink:to="loc_us-gaap_HedgingDesignationDomain_ee068c59-68bd-4668-8904-3689f6db9e57_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_a3c2da97-eb83-4464-a913-f894dfc55b51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_ee068c59-68bd-4668-8904-3689f6db9e57" xlink:to="loc_us-gaap_HedgingDesignationDomain_a3c2da97-eb83-4464-a913-f894dfc55b51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_ec6d6618-6884-42e3-ab9d-9970f3e4b43a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_a3c2da97-eb83-4464-a913-f894dfc55b51" xlink:to="loc_us-gaap_NondesignatedMember_ec6d6618-6884-42e3-ab9d-9970f3e4b43a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_479e6e34-f40d-4305-a1a0-4cd1188cf589" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_0cb32926-6014-414c-a907-c8a3280bb5e7" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_479e6e34-f40d-4305-a1a0-4cd1188cf589" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_479e6e34-f40d-4305-a1a0-4cd1188cf589_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_479e6e34-f40d-4305-a1a0-4cd1188cf589" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_479e6e34-f40d-4305-a1a0-4cd1188cf589_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_c664540b-533b-445a-84d5-138adcf2686d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_479e6e34-f40d-4305-a1a0-4cd1188cf589" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_c664540b-533b-445a-84d5-138adcf2686d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_CustomerDerivativesAndDealerOffsetsMember_993b486b-0b6c-4681-9b25-f0c8a2052b69" xlink:href="ucbi-20230331.xsd#ucbi_CustomerDerivativesAndDealerOffsetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_c664540b-533b-445a-84d5-138adcf2686d" xlink:to="loc_ucbi_CustomerDerivativesAndDealerOffsetsMember_993b486b-0b6c-4681-9b25-f0c8a2052b69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_BifurcatedEmbeddedDerivativesAndDealerOffsetsMember_5ecb46ce-8695-4bc5-881d-606c3c498feb" xlink:href="ucbi-20230331.xsd#ucbi_BifurcatedEmbeddedDerivativesAndDealerOffsetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_c664540b-533b-445a-84d5-138adcf2686d" xlink:to="loc_ucbi_BifurcatedEmbeddedDerivativesAndDealerOffsetsMember_5ecb46ce-8695-4bc5-881d-606c3c498feb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_MortgageBankingDerivativesMember_24863b93-1f71-42b3-bbf3-755af49ec441" xlink:href="ucbi-20230331.xsd#ucbi_MortgageBankingDerivativesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_c664540b-533b-445a-84d5-138adcf2686d" xlink:to="loc_ucbi_MortgageBankingDerivativesMember_24863b93-1f71-42b3-bbf3-755af49ec441" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_RiskParticipationsMember_65a42381-a0f7-4726-8be5-461854e4a443" xlink:href="ucbi-20230331.xsd#ucbi_RiskParticipationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_c664540b-533b-445a-84d5-138adcf2686d" xlink:to="loc_ucbi_RiskParticipationsMember_65a42381-a0f7-4726-8be5-461854e4a443" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/GoodwillandOtherIntangibleAssetsCarryingAmountDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#GoodwillandOtherIntangibleAssetsCarryingAmountDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/GoodwillandOtherIntangibleAssetsCarryingAmountDetails" xlink:type="extended" id="i09a8060771c941049f7eee2641c964ff_GoodwillandOtherIntangibleAssetsCarryingAmountDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fbb60e11-453b-49bf-8ab0-a73866347a5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetIncludingGoodwillAbstract_30443302-fb40-448e-ae50-3d78e529a697" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsNetIncludingGoodwillAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fbb60e11-453b-49bf-8ab0-a73866347a5a" xlink:to="loc_us-gaap_IntangibleAssetsNetIncludingGoodwillAbstract_30443302-fb40-448e-ae50-3d78e529a697" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_d653889d-157e-45f6-8a01-2928772c7ccb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IntangibleAssetsNetIncludingGoodwillAbstract_30443302-fb40-448e-ae50-3d78e529a697" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_d653889d-157e-45f6-8a01-2928772c7ccb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_19ae22e3-6b79-49a1-a453-0729df39fd1e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IntangibleAssetsNetIncludingGoodwillAbstract_30443302-fb40-448e-ae50-3d78e529a697" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_19ae22e3-6b79-49a1-a453-0729df39fd1e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_3020d897-fd21-48e3-b102-152458a20d92" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IntangibleAssetsNetIncludingGoodwillAbstract_30443302-fb40-448e-ae50-3d78e529a697" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_3020d897-fd21-48e3-b102-152458a20d92" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_84367359-4d99-479e-880f-7a250a14fd02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IntangibleAssetsNetIncludingGoodwillAbstract_30443302-fb40-448e-ae50-3d78e529a697" xlink:to="loc_us-gaap_Goodwill_84367359-4d99-479e-880f-7a250a14fd02" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_5246622c-a9f7-47f0-9556-ee1464cc42ad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsNetIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IntangibleAssetsNetIncludingGoodwillAbstract_30443302-fb40-448e-ae50-3d78e529a697" xlink:to="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_5246622c-a9f7-47f0-9556-ee1464cc42ad" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_90f90a99-fe82-409a-b326-efd07daa77b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fbb60e11-453b-49bf-8ab0-a73866347a5a" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_90f90a99-fe82-409a-b326-efd07daa77b9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c0546329-07b7-4912-af6a-525f9eaabf25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_90f90a99-fe82-409a-b326-efd07daa77b9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c0546329-07b7-4912-af6a-525f9eaabf25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c0546329-07b7-4912-af6a-525f9eaabf25_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c0546329-07b7-4912-af6a-525f9eaabf25" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c0546329-07b7-4912-af6a-525f9eaabf25_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ae88c1e0-2fc6-4d8a-b898-a7e40dce4e2d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c0546329-07b7-4912-af6a-525f9eaabf25" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ae88c1e0-2fc6-4d8a-b898-a7e40dce4e2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CoreDepositsMember_e493e51e-9460-44e9-8c95-93ae6bd182e1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CoreDepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ae88c1e0-2fc6-4d8a-b898-a7e40dce4e2d" xlink:to="loc_us-gaap_CoreDepositsMember_e493e51e-9460-44e9-8c95-93ae6bd182e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_89eadc0d-f4b3-4157-bc88-2b8e726aa54f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ae88c1e0-2fc6-4d8a-b898-a7e40dce4e2d" xlink:to="loc_us-gaap_CustomerRelationshipsMember_89eadc0d-f4b3-4157-bc88-2b8e726aa54f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/GoodwillandOtherIntangibleAssetsNarrativeDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#GoodwillandOtherIntangibleAssetsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/GoodwillandOtherIntangibleAssetsNarrativeDetails" xlink:type="extended" id="iba22cf20ab7247a094d83df36435f356_GoodwillandOtherIntangibleAssetsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fddf5836-ec9b-4030-8c2f-b7693c039e95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_c8d117f0-65e3-4ea0-966d-77a1587f8dc1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fddf5836-ec9b-4030-8c2f-b7693c039e95" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_c8d117f0-65e3-4ea0-966d-77a1587f8dc1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f431baf2-f878-4178-bb64-0296389b1c3d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_fddf5836-ec9b-4030-8c2f-b7693c039e95" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f431baf2-f878-4178-bb64-0296389b1c3d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b77919cd-7798-43bd-8a11-36e573ba46a8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f431baf2-f878-4178-bb64-0296389b1c3d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b77919cd-7798-43bd-8a11-36e573ba46a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b77919cd-7798-43bd-8a11-36e573ba46a8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b77919cd-7798-43bd-8a11-36e573ba46a8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b77919cd-7798-43bd-8a11-36e573ba46a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3390dc76-22dd-4fe0-83ce-4e6e7d02f0db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b77919cd-7798-43bd-8a11-36e573ba46a8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3390dc76-22dd-4fe0-83ce-4e6e7d02f0db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_2e4849ce-28d4-4787-bddf-537b89a2032a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_3390dc76-22dd-4fe0-83ce-4e6e7d02f0db" xlink:to="loc_us-gaap_CustomerRelationshipsMember_2e4849ce-28d4-4787-bddf-537b89a2032a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_2ce331e0-13f6-4436-8508-a348f60dfa00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f431baf2-f878-4178-bb64-0296389b1c3d" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_2ce331e0-13f6-4436-8508-a348f60dfa00" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2ce331e0-13f6-4436-8508-a348f60dfa00_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2ce331e0-13f6-4436-8508-a348f60dfa00" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2ce331e0-13f6-4436-8508-a348f60dfa00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_000219e9-ae62-40a6-be02-f14054faf721" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_2ce331e0-13f6-4436-8508-a348f60dfa00" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_000219e9-ae62-40a6-be02-f14054faf721" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ProgressBankTrustMember_bf849b55-a26c-4aa0-8852-a1af392009c6" xlink:href="ucbi-20230331.xsd#ucbi_ProgressBankTrustMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_000219e9-ae62-40a6-be02-f14054faf721" xlink:to="loc_ucbi_ProgressBankTrustMember_bf849b55-a26c-4aa0-8852-a1af392009c6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/ShorttermBorrowingsandFHLBAdvancesRepurchaseAgreementsareSecuredBorrowingsDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#ShorttermBorrowingsandFHLBAdvancesRepurchaseAgreementsareSecuredBorrowingsDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/ShorttermBorrowingsandFHLBAdvancesRepurchaseAgreementsareSecuredBorrowingsDetails" xlink:type="extended" id="id045f2e259624b66a3431a62b04b82a2_ShorttermBorrowingsandFHLBAdvancesRepurchaseAgreementsareSecuredBorrowingsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtLineItems_a2d3a154-788f-4c21-92b5-c5bed4d263e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_8e70c8a2-f175-47fa-8f9b-e71a96b216bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_a2d3a154-788f-4c21-92b5-c5bed4d263e7" xlink:to="loc_us-gaap_ShortTermBorrowings_8e70c8a2-f175-47fa-8f9b-e71a96b216bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShortTermDebtTable_679136c3-b17f-40c0-a51b-470b80a5b5d3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShortTermDebtTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShortTermDebtLineItems_a2d3a154-788f-4c21-92b5-c5bed4d263e7" xlink:to="loc_us-gaap_ScheduleOfShortTermDebtTable_679136c3-b17f-40c0-a51b-470b80a5b5d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_e0202a89-d6fb-4b87-b11b-4fd9f7299478" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_679136c3-b17f-40c0-a51b-470b80a5b5d3" xlink:to="loc_us-gaap_FinancialInstrumentAxis_e0202a89-d6fb-4b87-b11b-4fd9f7299478" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e0202a89-d6fb-4b87-b11b-4fd9f7299478_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_e0202a89-d6fb-4b87-b11b-4fd9f7299478" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_e0202a89-d6fb-4b87-b11b-4fd9f7299478_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bf7f7e70-ec14-4bad-9883-229248faf30d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_e0202a89-d6fb-4b87-b11b-4fd9f7299478" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bf7f7e70-ec14-4bad-9883-229248faf30d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_2bf56d52-2200-4c21-9ead-85ac4d0bfa3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bf7f7e70-ec14-4bad-9883-229248faf30d" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_2bf56d52-2200-4c21-9ead-85ac4d0bfa3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_816ae110-7d48-4af7-9dcd-d666865f9215" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_bf7f7e70-ec14-4bad-9883-229248faf30d" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_816ae110-7d48-4af7-9dcd-d666865f9215" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_b63566e3-30a9-4293-927b-25fd15b80619" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShortTermDebtTable_679136c3-b17f-40c0-a51b-470b80a5b5d3" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_b63566e3-30a9-4293-927b-25fd15b80619" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_b63566e3-30a9-4293-927b-25fd15b80619_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_b63566e3-30a9-4293-927b-25fd15b80619" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_b63566e3-30a9-4293-927b-25fd15b80619_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_8820ae9c-0944-42a5-96e9-acd871209068" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodsAxis_b63566e3-30a9-4293-927b-25fd15b80619" xlink:to="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_8820ae9c-0944-42a5-96e9-acd871209068" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaturityOvernightMember_76257032-cd6a-4c9d-b000-f84fcf024b43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MaturityOvernightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_8820ae9c-0944-42a5-96e9-acd871209068" xlink:to="loc_us-gaap_MaturityOvernightMember_76257032-cd6a-4c9d-b000-f84fcf024b43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaturityUpTo30DaysMember_3f178a43-4825-4507-b569-46cbfbfc1d57" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MaturityUpTo30DaysMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_8820ae9c-0944-42a5-96e9-acd871209068" xlink:to="loc_us-gaap_MaturityUpTo30DaysMember_3f178a43-4825-4507-b569-46cbfbfc1d57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Maturity30To90DaysMember_43e67b20-dba5-4b28-b319-14ac63c90f55" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Maturity30To90DaysMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_8820ae9c-0944-42a5-96e9-acd871209068" xlink:to="loc_us-gaap_Maturity30To90DaysMember_43e67b20-dba5-4b28-b319-14ac63c90f55" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaturityOver90DaysMember_7ff42ccf-3264-4778-abcd-ef48d98903f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MaturityOver90DaysMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsSoldUnderAgreementsToRepurchaseMaturityPeriodDomain_8820ae9c-0944-42a5-96e9-acd871209068" xlink:to="loc_us-gaap_MaturityOver90DaysMember_7ff42ccf-3264-4778-abcd-ef48d98903f4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValueAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AssetsandLiabilitiesMeasuredatFairValueAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValueAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="extended" id="i4d373c99c92f455f9faed693e82797d3_AssetsandLiabilitiesMeasuredatFairValueAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_39162184-95e3-4633-b652-deab18cc9770" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_39162184-95e3-4633-b652-deab18cc9770" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_a23d5807-cfa9-4f30-a5ff-e16fda1af9d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_a23d5807-cfa9-4f30-a5ff-e16fda1af9d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNi_f9d4fb64-4aac-4985-b17c-e27cefe32171" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNi"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:to="loc_us-gaap_EquitySecuritiesFvNi_f9d4fb64-4aac-4985-b17c-e27cefe32171" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgagesHeldForSaleFairValueDisclosure_b2073e24-4fcb-4ec1-af2e-fbdb0438245b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MortgagesHeldForSaleFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:to="loc_us-gaap_MortgagesHeldForSaleFairValueDisclosure_b2073e24-4fcb-4ec1-af2e-fbdb0438245b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_399aa2c5-5d1d-45b3-a390-6b3198965bac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredCompensationPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_399aa2c5-5d1d-45b3-a390-6b3198965bac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetAtFairValueAmount_a5432961-ac92-4edb-8b68-b363834a6070" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServicingAssetAtFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:to="loc_us-gaap_ServicingAssetAtFairValueAmount_a5432961-ac92-4edb-8b68-b363834a6070" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageServicingAssetAtFairValueAmount_a81d394c-eded-4eff-b45c-cba8bf8c845b" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageServicingAssetAtFairValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:to="loc_ucbi_ResidentialMortgageServicingAssetAtFairValueAmount_a81d394c-eded-4eff-b45c-cba8bf8c845b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_7669aa62-f67a-4445-a5ae-39c9e089745c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:to="loc_us-gaap_DerivativeAssets_7669aa62-f67a-4445-a5ae-39c9e089745c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_464e9d1c-63c9-4827-a15e-3fdd406a1877" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_d506f01b-a82e-4ebb-aa1c-f0300d7f8351" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_464e9d1c-63c9-4827-a15e-3fdd406a1877" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71013cee-0d25-4051-8dfa-dfb9b92408c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_39162184-95e3-4633-b652-deab18cc9770" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71013cee-0d25-4051-8dfa-dfb9b92408c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent_81d602ec-5480-40ea-94a7-d0952434f968" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71013cee-0d25-4051-8dfa-dfb9b92408c4" xlink:to="loc_us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent_81d602ec-5480-40ea-94a7-d0952434f968" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_bf8190b5-b2c4-45a9-88ac-1516d553bd44" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71013cee-0d25-4051-8dfa-dfb9b92408c4" xlink:to="loc_us-gaap_DerivativeLiabilities_bf8190b5-b2c4-45a9-88ac-1516d553bd44" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_f78ca49f-7969-4ab2-83e4-c80f9b8b03da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_71013cee-0d25-4051-8dfa-dfb9b92408c4" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_f78ca49f-7969-4ab2-83e4-c80f9b8b03da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f863214a-4a5d-40f5-92f3-4f12884870fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_39162184-95e3-4633-b652-deab18cc9770" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f863214a-4a5d-40f5-92f3-4f12884870fc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3a121e8e-dc1d-48f5-9a36-1a334b3e29fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f863214a-4a5d-40f5-92f3-4f12884870fc" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3a121e8e-dc1d-48f5-9a36-1a334b3e29fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3a121e8e-dc1d-48f5-9a36-1a334b3e29fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3a121e8e-dc1d-48f5-9a36-1a334b3e29fc" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3a121e8e-dc1d-48f5-9a36-1a334b3e29fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_52bbd801-8846-4786-841a-cbc4a5bd8df3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3a121e8e-dc1d-48f5-9a36-1a334b3e29fc" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_52bbd801-8846-4786-841a-cbc4a5bd8df3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_00d0f10e-05df-4f41-8cbe-7fcd595113f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_52bbd801-8846-4786-841a-cbc4a5bd8df3" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_00d0f10e-05df-4f41-8cbe-7fcd595113f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ee63b008-2853-44cb-b69b-c0ff3b256121" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f863214a-4a5d-40f5-92f3-4f12884870fc" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ee63b008-2853-44cb-b69b-c0ff3b256121" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ee63b008-2853-44cb-b69b-c0ff3b256121_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ee63b008-2853-44cb-b69b-c0ff3b256121" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ee63b008-2853-44cb-b69b-c0ff3b256121_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9b9291-11e5-4538-a4fe-c320171c5a2d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ee63b008-2853-44cb-b69b-c0ff3b256121" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9b9291-11e5-4538-a4fe-c320171c5a2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_65652783-a571-41f1-92d3-084040870c82" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9b9291-11e5-4538-a4fe-c320171c5a2d" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_65652783-a571-41f1-92d3-084040870c82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_b6c5afb0-6290-493a-9d09-60b97e816b87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9b9291-11e5-4538-a4fe-c320171c5a2d" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_b6c5afb0-6290-493a-9d09-60b97e816b87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_6e8fba42-7527-411f-87fc-2c88c1488957" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0e9b9291-11e5-4538-a4fe-c320171c5a2d" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_6e8fba42-7527-411f-87fc-2c88c1488957" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_57ce18e0-a5e3-4da7-ab6a-bcaa371d9241" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_f863214a-4a5d-40f5-92f3-4f12884870fc" xlink:to="loc_us-gaap_FinancialInstrumentAxis_57ce18e0-a5e3-4da7-ab6a-bcaa371d9241" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_57ce18e0-a5e3-4da7-ab6a-bcaa371d9241_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_57ce18e0-a5e3-4da7-ab6a-bcaa371d9241" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_57ce18e0-a5e3-4da7-ab6a-bcaa371d9241_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_57ce18e0-a5e3-4da7-ab6a-bcaa371d9241" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USTreasurySecuritiesMember_55b7bb59-1fcc-47e9-b005-4824c2e01388" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USTreasurySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:to="loc_us-gaap_USTreasurySecuritiesMember_55b7bb59-1fcc-47e9-b005-4824c2e01388" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_340aea45-3b11-468e-9eaa-8a1cb9b75161" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_340aea45-3b11-468e-9eaa-8a1cb9b75161" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_a28fadcf-c7ad-4246-9ea1-fa1cf3489969" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_a28fadcf-c7ad-4246-9ea1-fa1cf3489969" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_3815c95e-13b6-47d7-9f46-f55bdfb7532a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResidentialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:to="loc_us-gaap_ResidentialMortgageBackedSecuritiesMember_3815c95e-13b6-47d7-9f46-f55bdfb7532a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_9c1a2fda-94f1-4008-8b33-923cdd616ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_9c1a2fda-94f1-4008-8b33-923cdd616ce4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_fcd8f9e7-3c67-4ed8-8154-cf10f78553dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_fcd8f9e7-3c67-4ed8-8154-cf10f78553dc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_11539c8a-b931-455d-abce-33949706d5c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_2c10c8c6-fd11-4bd3-952c-e726abb92828" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_11539c8a-b931-455d-abce-33949706d5c9" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValueReconciliationofAssetsMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AssetsandLiabilitiesMeasuredatFairValueReconciliationofAssetsMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValueReconciliationofAssetsMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails" xlink:type="extended" id="i10b6770931904de9987ccf104399676a_AssetsandLiabilitiesMeasuredatFairValueReconciliationofAssetsMeasuredatFairValueonaRecurringBasisUsingSignificantUnobservableInputsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_91c62ea6-20a0-4443-beb3-c78a1cc92348" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_91c62ea6-20a0-4443-beb3-c78a1cc92348" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_6132c756-1dbd-4fb9-abc0-4b2f0dde788c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_6132c756-1dbd-4fb9-abc0-4b2f0dde788c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetBusinessCombinationAndProvisionalAdjustment_1ca79129-6560-42db-9d77-e3b622d608ff" xlink:href="ucbi-20230331.xsd#ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetBusinessCombinationAndProvisionalAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:to="loc_ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetBusinessCombinationAndProvisionalAdjustment_1ca79129-6560-42db-9d77-e3b622d608ff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues_577a7e79-be0a-4fc7-9dc5-3178599e848c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues_577a7e79-be0a-4fc7-9dc5-3178599e848c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_c96454ce-c6ad-4a90-8ade-5e0d5cce6326" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3_c96454ce-c6ad-4a90-8ade-5e0d5cce6326" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSalesAndSettlements_2a8d3eb6-e473-4f15-b48f-ce65c5edd30a" xlink:href="ucbi-20230331.xsd#ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSalesAndSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:to="loc_ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSalesAndSettlements_2a8d3eb6-e473-4f15-b48f-ce65c5edd30a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_2614acee-cbdd-4ca8-abc6-b88b6d0f6c1c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss_2614acee-cbdd-4ca8-abc6-b88b6d0f6c1c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_9603b68d-82c9-4238-a1df-a202ce090e9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_50ca3410-fe61-4a7e-a52a-2765d8541c58" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1_9603b68d-82c9-4238-a1df-a202ce090e9f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_5819b4b2-24a8-4187-9e4a-7691ba3b8f93" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_91c62ea6-20a0-4443-beb3-c78a1cc92348" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_5b26de41-4148-4f7c-82a2-8d20bb5a3f61" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_5b26de41-4148-4f7c-82a2-8d20bb5a3f61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityBusinessCombinationAndProvisionalAdjustment_0ab6f2d4-e669-4647-a5c5-5356a1462600" xlink:href="ucbi-20230331.xsd#ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityBusinessCombinationAndProvisionalAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:to="loc_ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityBusinessCombinationAndProvisionalAdjustment_0ab6f2d4-e669-4647-a5c5-5356a1462600" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues_4aeadda6-0e0f-4cd1-9819-dfa82ff86a4f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityIssues_4aeadda6-0e0f-4cd1-9819-dfa82ff86a4f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3_2140c837-c6bd-4760-9407-c47d44384046" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationLiabilityTransfersOutOfLevel3_2140c837-c6bd-4760-9407-c47d44384046" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySalesAndSettlements_790d91bb-eca8-41c3-898b-b5df7129e3c6" xlink:href="ucbi-20230331.xsd#ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySalesAndSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:to="loc_ucbi_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySalesAndSettlements_790d91bb-eca8-41c3-898b-b5df7129e3c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome_58502f33-09f9-4393-9edd-46551a0f8f40" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInOtherComprehensiveIncome_58502f33-09f9-4393-9edd-46551a0f8f40" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_cc92550c-64e2-4365-8a56-934a20d04866" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_204074a5-6ea8-40c4-9846-914d08ed3518" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings_cc92550c-64e2-4365-8a56-934a20d04866" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_abf01524-09de-4334-9f18-8cd0f692a46b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83c83213-3b83-4e39-a869-a66d906434b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_91c62ea6-20a0-4443-beb3-c78a1cc92348" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83c83213-3b83-4e39-a869-a66d906434b9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_fe982378-2873-4760-8131-d61391017fde" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83c83213-3b83-4e39-a869-a66d906434b9" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_fe982378-2873-4760-8131-d61391017fde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_fe982378-2873-4760-8131-d61391017fde_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_fe982378-2873-4760-8131-d61391017fde" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_fe982378-2873-4760-8131-d61391017fde_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_5c196577-31bf-44cd-9a9d-c6a64935c5ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_fe982378-2873-4760-8131-d61391017fde" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_5c196577-31bf-44cd-9a9d-c6a64935c5ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_d11273e1-3066-42d9-a87d-16a27595cbd2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_5c196577-31bf-44cd-9a9d-c6a64935c5ca" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_d11273e1-3066-42d9-a87d-16a27595cbd2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1392e72f-1384-4387-a662-423ff7fb8de0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83c83213-3b83-4e39-a869-a66d906434b9" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1392e72f-1384-4387-a662-423ff7fb8de0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1392e72f-1384-4387-a662-423ff7fb8de0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1392e72f-1384-4387-a662-423ff7fb8de0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1392e72f-1384-4387-a662-423ff7fb8de0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e90d3474-789f-4ecf-97b0-f378374d08f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_1392e72f-1384-4387-a662-423ff7fb8de0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e90d3474-789f-4ecf-97b0-f378374d08f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_ecb493d1-b6d6-4563-b71f-e4f2036e4e74" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e90d3474-789f-4ecf-97b0-f378374d08f2" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_ecb493d1-b6d6-4563-b71f-e4f2036e4e74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_81681f8c-e0a9-4b25-803a-d49223cbf0eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83c83213-3b83-4e39-a869-a66d906434b9" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_81681f8c-e0a9-4b25-803a-d49223cbf0eb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_81681f8c-e0a9-4b25-803a-d49223cbf0eb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_81681f8c-e0a9-4b25-803a-d49223cbf0eb" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_81681f8c-e0a9-4b25-803a-d49223cbf0eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3805f5f8-d6bb-4448-9ce4-eb10cb0ddf9e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_81681f8c-e0a9-4b25-803a-d49223cbf0eb" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3805f5f8-d6bb-4448-9ce4-eb10cb0ddf9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_541a5086-9526-42e2-accd-46b4cc81c16d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_3805f5f8-d6bb-4448-9ce4-eb10cb0ddf9e" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_541a5086-9526-42e2-accd-46b4cc81c16d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_581fd6f8-0828-4ca3-82c8-f3e4b4924e3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_83c83213-3b83-4e39-a869-a66d906434b9" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_581fd6f8-0828-4ca3-82c8-f3e4b4924e3e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_581fd6f8-0828-4ca3-82c8-f3e4b4924e3e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_581fd6f8-0828-4ca3-82c8-f3e4b4924e3e" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_581fd6f8-0828-4ca3-82c8-f3e4b4924e3e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_0bc2807a-9a04-48a8-9e37-71779bc94a07" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_581fd6f8-0828-4ca3-82c8-f3e4b4924e3e" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_0bc2807a-9a04-48a8-9e37-71779bc94a07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DerivativeAssetMember_78664409-a39f-476d-b728-509cf79bd2f4" xlink:href="ucbi-20230331.xsd#ucbi_DerivativeAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_0bc2807a-9a04-48a8-9e37-71779bc94a07" xlink:to="loc_ucbi_DerivativeAssetMember_78664409-a39f-476d-b728-509cf79bd2f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_SBAServicingRightsMember_d460289a-e191-4c46-9170-5a5ca17689a9" xlink:href="ucbi-20230331.xsd#ucbi_SBAServicingRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_0bc2807a-9a04-48a8-9e37-71779bc94a07" xlink:to="loc_ucbi_SBAServicingRightsMember_d460289a-e191-4c46-9170-5a5ca17689a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageServicingRightsMember_e1d44950-4b45-49e2-9a09-8d4e990781e0" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageServicingRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_0bc2807a-9a04-48a8-9e37-71779bc94a07" xlink:to="loc_ucbi_ResidentialMortgageServicingRightsMember_e1d44950-4b45-49e2-9a09-8d4e990781e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_045ed432-7985-4a26-a212-c81971b67b12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_0bc2807a-9a04-48a8-9e37-71779bc94a07" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_045ed432-7985-4a26-a212-c81971b67b12" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsforFairValueonaRecurringBasisDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AssetsandLiabilitiesMeasuredatFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsforFairValueonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsforFairValueonaRecurringBasisDetails" xlink:type="extended" id="i744ef8730bb0481aa7ebd6fc3912c991_AssetsandLiabilitiesMeasuredatFairValueQuantitativeInformationAboutLevel3FairValueMeasurementsforFairValueonaRecurringBasisDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_a5111323-795c-47dd-8b63-7e5ca47a063c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServicingAssetMeasurementInput_59f2a92f-7460-4103-8a98-3d592c0a1d33" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServicingAssetMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_a5111323-795c-47dd-8b63-7e5ca47a063c" xlink:to="loc_us-gaap_ServicingAssetMeasurementInput_59f2a92f-7460-4103-8a98-3d592c0a1d33" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageServicingAssetMeasurementInput_6cbe74c8-0dc8-457f-a336-0e18e14fdd9b" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageServicingAssetMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_a5111323-795c-47dd-8b63-7e5ca47a063c" xlink:to="loc_ucbi_ResidentialMortgageServicingAssetMeasurementInput_6cbe74c8-0dc8-457f-a336-0e18e14fdd9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput_1586ac6c-cb69-4411-9803-d547406fd071" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_a5111323-795c-47dd-8b63-7e5ca47a063c" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleMeasurementInput_1586ac6c-cb69-4411-9803-d547406fd071" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetMeasurementInput_e50fb5fc-65be-43b5-8555-ed768a5f97ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_a5111323-795c-47dd-8b63-7e5ca47a063c" xlink:to="loc_us-gaap_DerivativeAssetMeasurementInput_e50fb5fc-65be-43b5-8555-ed768a5f97ef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d11ef4ff-ee52-4400-91eb-da96d58a1dce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_a5111323-795c-47dd-8b63-7e5ca47a063c" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d11ef4ff-ee52-4400-91eb-da96d58a1dce" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_88b2a17a-814b-4446-90f7-bba7280ce373" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d11ef4ff-ee52-4400-91eb-da96d58a1dce" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_88b2a17a-814b-4446-90f7-bba7280ce373" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_88b2a17a-814b-4446-90f7-bba7280ce373_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_88b2a17a-814b-4446-90f7-bba7280ce373" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_88b2a17a-814b-4446-90f7-bba7280ce373_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_1558e8e1-fda9-446a-94ee-b2b0c01064f6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_88b2a17a-814b-4446-90f7-bba7280ce373" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_1558e8e1-fda9-446a-94ee-b2b0c01064f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_315e5f46-8470-480f-9c05-238c1f168053" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_1558e8e1-fda9-446a-94ee-b2b0c01064f6" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_315e5f46-8470-480f-9c05-238c1f168053" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2b1cdbd1-a98f-4111-ae90-c84299c69c7f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d11ef4ff-ee52-4400-91eb-da96d58a1dce" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2b1cdbd1-a98f-4111-ae90-c84299c69c7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2b1cdbd1-a98f-4111-ae90-c84299c69c7f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2b1cdbd1-a98f-4111-ae90-c84299c69c7f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2b1cdbd1-a98f-4111-ae90-c84299c69c7f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_16f36cc5-31a7-4f5f-a7cd-deac08507502" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2b1cdbd1-a98f-4111-ae90-c84299c69c7f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_16f36cc5-31a7-4f5f-a7cd-deac08507502" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_5ae99e45-3dc1-4318-a307-2470e2da92ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_16f36cc5-31a7-4f5f-a7cd-deac08507502" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_5ae99e45-3dc1-4318-a307-2470e2da92ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_16862738-290f-4df3-bf5c-6befa707dfa4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d11ef4ff-ee52-4400-91eb-da96d58a1dce" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_16862738-290f-4df3-bf5c-6befa707dfa4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_16862738-290f-4df3-bf5c-6befa707dfa4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_16862738-290f-4df3-bf5c-6befa707dfa4" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_16862738-290f-4df3-bf5c-6befa707dfa4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_85628932-46b6-40fa-9ec8-4ad4db8d1454" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_16862738-290f-4df3-bf5c-6befa707dfa4" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_85628932-46b6-40fa-9ec8-4ad4db8d1454" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_SBAServicingRightsMember_6edb250e-f348-4d27-a958-50d0345b55a5" xlink:href="ucbi-20230331.xsd#ucbi_SBAServicingRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_85628932-46b6-40fa-9ec8-4ad4db8d1454" xlink:to="loc_ucbi_SBAServicingRightsMember_6edb250e-f348-4d27-a958-50d0345b55a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ResidentialMortgageServicingRightsMember_2ab00ca7-bdff-48a8-928e-cd3a96813492" xlink:href="ucbi-20230331.xsd#ucbi_ResidentialMortgageServicingRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_85628932-46b6-40fa-9ec8-4ad4db8d1454" xlink:to="loc_ucbi_ResidentialMortgageServicingRightsMember_2ab00ca7-bdff-48a8-928e-cd3a96813492" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_15ca8ebc-0a93-45f5-82da-5532a8d30871" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_85628932-46b6-40fa-9ec8-4ad4db8d1454" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_15ca8ebc-0a93-45f5-82da-5532a8d30871" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_DerivativeAssetsMortgageMember_58ba10b4-67b9-4486-bf8e-4aa7359171db" xlink:href="ucbi-20230331.xsd#ucbi_DerivativeAssetsMortgageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_85628932-46b6-40fa-9ec8-4ad4db8d1454" xlink:to="loc_ucbi_DerivativeAssetsMortgageMember_58ba10b4-67b9-4486-bf8e-4aa7359171db" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_b977e595-83af-4d76-bd71-f034b613818c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d11ef4ff-ee52-4400-91eb-da96d58a1dce" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_b977e595-83af-4d76-bd71-f034b613818c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_b977e595-83af-4d76-bd71-f034b613818c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_b977e595-83af-4d76-bd71-f034b613818c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_b977e595-83af-4d76-bd71-f034b613818c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_93d13c56-4ece-4e57-b796-a3d61eb46bc7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_b977e595-83af-4d76-bd71-f034b613818c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_93d13c56-4ece-4e57-b796-a3d61eb46bc7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_027665c2-25b3-4552-bb51-def2c6fd978a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_93d13c56-4ece-4e57-b796-a3d61eb46bc7" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_027665c2-25b3-4552-bb51-def2c6fd978a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputPrepaymentRateMember_249f650c-b95c-445b-80cf-a8b11a3a3b28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputPrepaymentRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_93d13c56-4ece-4e57-b796-a3d61eb46bc7" xlink:to="loc_us-gaap_MeasurementInputPrepaymentRateMember_249f650c-b95c-445b-80cf-a8b11a3a3b28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_MeasurementInputPullThroughRateMember_b3e9c616-23f5-488e-815c-794300d21943" xlink:href="ucbi-20230331.xsd#ucbi_MeasurementInputPullThroughRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_93d13c56-4ece-4e57-b796-a3d61eb46bc7" xlink:to="loc_ucbi_MeasurementInputPullThroughRateMember_b3e9c616-23f5-488e-815c-794300d21943" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_e9b89dab-ed0b-4989-84e5-1434764584a0" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d11ef4ff-ee52-4400-91eb-da96d58a1dce" xlink:to="loc_srt_RangeAxis_e9b89dab-ed0b-4989-84e5-1434764584a0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e9b89dab-ed0b-4989-84e5-1434764584a0_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_e9b89dab-ed0b-4989-84e5-1434764584a0" xlink:to="loc_srt_RangeMember_e9b89dab-ed0b-4989-84e5-1434764584a0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_fded5f3a-7d0b-4b7b-ae62-c358d70c0095" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_e9b89dab-ed0b-4989-84e5-1434764584a0" xlink:to="loc_srt_RangeMember_fded5f3a-7d0b-4b7b-ae62-c358d70c0095" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_8399fbdf-5ecf-41f8-9750-71c8edac4c00" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_fded5f3a-7d0b-4b7b-ae62-c358d70c0095" xlink:to="loc_srt_MinimumMember_8399fbdf-5ecf-41f8-9750-71c8edac4c00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_8859e09a-c5df-4239-a139-52dc01add52b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_fded5f3a-7d0b-4b7b-ae62-c358d70c0095" xlink:to="loc_srt_MaximumMember_8859e09a-c5df-4239-a139-52dc01add52b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_6e8d186a-6c42-446c-b19e-a158b5f6e762" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_fded5f3a-7d0b-4b7b-ae62-c358d70c0095" xlink:to="loc_srt_WeightedAverageMember_6e8d186a-6c42-446c-b19e-a158b5f6e762" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValuePresentationofAssetsMeasuredatFairValueonNonrecurringBasisDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AssetsandLiabilitiesMeasuredatFairValuePresentationofAssetsMeasuredatFairValueonNonrecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValuePresentationofAssetsMeasuredatFairValueonNonrecurringBasisDetails" xlink:type="extended" id="iea230b3f275b4bd9a30c767274420b1a_AssetsandLiabilitiesMeasuredatFairValuePresentationofAssetsMeasuredatFairValueonNonrecurringBasisDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_b93a9cff-dbf2-40db-8ed5-1925078c477d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_LoansHeldForInvestmentAfterNonrecurringFairValueAdjustmentCarryingValue_c0b2db25-baa3-4ca9-914a-d9e89d960949" xlink:href="ucbi-20230331.xsd#ucbi_LoansHeldForInvestmentAfterNonrecurringFairValueAdjustmentCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_b93a9cff-dbf2-40db-8ed5-1925078c477d" xlink:to="loc_ucbi_LoansHeldForInvestmentAfterNonrecurringFairValueAdjustmentCarryingValue_c0b2db25-baa3-4ca9-914a-d9e89d960949" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_MortgagesHeldForSaleAfterNonrecurringFairValueAdjustmentCarryingValue_0ff42a99-ca11-401d-85f8-72e60aaa0a4a" xlink:href="ucbi-20230331.xsd#ucbi_MortgagesHeldForSaleAfterNonrecurringFairValueAdjustmentCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_b93a9cff-dbf2-40db-8ed5-1925078c477d" xlink:to="loc_ucbi_MortgagesHeldForSaleAfterNonrecurringFairValueAdjustmentCarryingValue_0ff42a99-ca11-401d-85f8-72e60aaa0a4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_b551a4e1-293f-4001-bfe6-a32d2ae3e82b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_b93a9cff-dbf2-40db-8ed5-1925078c477d" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_b551a4e1-293f-4001-bfe6-a32d2ae3e82b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_9853f6ac-b998-4af8-8966-aab5f729532c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_b551a4e1-293f-4001-bfe6-a32d2ae3e82b" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_9853f6ac-b998-4af8-8966-aab5f729532c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_9853f6ac-b998-4af8-8966-aab5f729532c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_9853f6ac-b998-4af8-8966-aab5f729532c" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_9853f6ac-b998-4af8-8966-aab5f729532c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3217b15c-459d-43f1-92ba-2a44d9fcb518" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_9853f6ac-b998-4af8-8966-aab5f729532c" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3217b15c-459d-43f1-92ba-2a44d9fcb518" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_a0e1ec72-6e47-4fa6-bf74-9e0ba3bae165" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsNonrecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_3217b15c-459d-43f1-92ba-2a44d9fcb518" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_a0e1ec72-6e47-4fa6-bf74-9e0ba3bae165" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a20cb2a1-1354-416f-b640-93a98f3c132d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_b551a4e1-293f-4001-bfe6-a32d2ae3e82b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a20cb2a1-1354-416f-b640-93a98f3c132d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_a20cb2a1-1354-416f-b640-93a98f3c132d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a20cb2a1-1354-416f-b640-93a98f3c132d" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_a20cb2a1-1354-416f-b640-93a98f3c132d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_54b89797-e6f4-4c50-9e78-3d0ec69ab7da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_a20cb2a1-1354-416f-b640-93a98f3c132d" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_54b89797-e6f4-4c50-9e78-3d0ec69ab7da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_9d9eb692-1de0-4e8e-bd21-0b83066e837b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_54b89797-e6f4-4c50-9e78-3d0ec69ab7da" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_9d9eb692-1de0-4e8e-bd21-0b83066e837b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_73344ad8-94b2-4f61-8e82-25a556048c48" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_54b89797-e6f4-4c50-9e78-3d0ec69ab7da" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_73344ad8-94b2-4f61-8e82-25a556048c48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_f83cc272-bd66-48e6-9927-fbb382242b3b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_54b89797-e6f4-4c50-9e78-3d0ec69ab7da" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_f83cc272-bd66-48e6-9927-fbb382242b3b" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValueCarryingAmountandFairValuesforOtherFinancialInstrumentsthatarenotMeasuredatFairValueonaRecurringBasisDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#AssetsandLiabilitiesMeasuredatFairValueCarryingAmountandFairValuesforOtherFinancialInstrumentsthatarenotMeasuredatFairValueonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/AssetsandLiabilitiesMeasuredatFairValueCarryingAmountandFairValuesforOtherFinancialInstrumentsthatarenotMeasuredatFairValueonaRecurringBasisDetails" xlink:type="extended" id="id795ac3a4cf543f58e30cabeaf8ed3c1_AssetsandLiabilitiesMeasuredatFairValueCarryingAmountandFairValuesforOtherFinancialInstrumentsthatarenotMeasuredatFairValueonaRecurringBasisDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_485195c3-14a6-4e24-9d1e-a66ff742db19" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_913f98aa-1233-457b-9e2e-80f3e269207a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_485195c3-14a6-4e24-9d1e-a66ff742db19" xlink:to="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_913f98aa-1233-457b-9e2e-80f3e269207a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HeldToMaturitySecuritiesFairValue_e18d61a4-fdb8-428e-bd12-5ee112678896" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HeldToMaturitySecuritiesFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_913f98aa-1233-457b-9e2e-80f3e269207a" xlink:to="loc_us-gaap_HeldToMaturitySecuritiesFairValue_e18d61a4-fdb8-428e-bd12-5ee112678896" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_a174af0d-85bd-42a9-98bf-055dccead7f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialAssetsBalanceSheetGroupingsAbstract_913f98aa-1233-457b-9e2e-80f3e269207a" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_a174af0d-85bd-42a9-98bf-055dccead7f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_177c54c5-585c-48fd-8230-42e726e4e110" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_485195c3-14a6-4e24-9d1e-a66ff742db19" xlink:to="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_177c54c5-585c-48fd-8230-42e726e4e110" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositsFairValueDisclosure_63e131aa-f443-470c-9c05-8a9527352662" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepositsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_177c54c5-585c-48fd-8230-42e726e4e110" xlink:to="loc_us-gaap_DepositsFairValueDisclosure_63e131aa-f443-470c-9c05-8a9527352662" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvancesFromFederalHomeLoanBanks_4b3a9b9b-7359-4651-9edf-933898d8a481" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdvancesFromFederalHomeLoanBanks"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_177c54c5-585c-48fd-8230-42e726e4e110" xlink:to="loc_us-gaap_AdvancesFromFederalHomeLoanBanks_4b3a9b9b-7359-4651-9edf-933898d8a481" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_d61b9248-d740-4bc6-9eea-09772d66cde4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialInstrumentsFinancialLiabilitiesBalanceSheetGroupingsAbstract_177c54c5-585c-48fd-8230-42e726e4e110" xlink:to="loc_us-gaap_LongTermDebtFairValue_d61b9248-d740-4bc6-9eea-09772d66cde4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c4ffaead-28c4-4976-bca6-1a1f43aac779" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_485195c3-14a6-4e24-9d1e-a66ff742db19" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c4ffaead-28c4-4976-bca6-1a1f43aac779" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_657a8943-d422-4830-b0ba-53ec8823fa94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c4ffaead-28c4-4976-bca6-1a1f43aac779" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_657a8943-d422-4830-b0ba-53ec8823fa94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_657a8943-d422-4830-b0ba-53ec8823fa94_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_657a8943-d422-4830-b0ba-53ec8823fa94" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_657a8943-d422-4830-b0ba-53ec8823fa94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_dd854dd8-a850-44d9-8aef-02f9f6ae1214" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_657a8943-d422-4830-b0ba-53ec8823fa94" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_dd854dd8-a850-44d9-8aef-02f9f6ae1214" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_0c938e7b-43ec-4187-baad-7d3f2a05ab42" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_dd854dd8-a850-44d9-8aef-02f9f6ae1214" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_0c938e7b-43ec-4187-baad-7d3f2a05ab42" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_e91754d5-a7c4-4e7a-bf87-3a2e5662ead0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_0c938e7b-43ec-4187-baad-7d3f2a05ab42" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_e91754d5-a7c4-4e7a-bf87-3a2e5662ead0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_b89ccba7-9f03-43d0-be8a-5bd94efff45d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_0c938e7b-43ec-4187-baad-7d3f2a05ab42" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_b89ccba7-9f03-43d0-be8a-5bd94efff45d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_edce8528-1b63-4a1d-bd06-cdab0706d44a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c4ffaead-28c4-4976-bca6-1a1f43aac779" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_edce8528-1b63-4a1d-bd06-cdab0706d44a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_edce8528-1b63-4a1d-bd06-cdab0706d44a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_edce8528-1b63-4a1d-bd06-cdab0706d44a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_edce8528-1b63-4a1d-bd06-cdab0706d44a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6f8a3567-fb55-488f-a6db-e2bb30775e05" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_edce8528-1b63-4a1d-bd06-cdab0706d44a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6f8a3567-fb55-488f-a6db-e2bb30775e05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_92b58883-76cb-4307-a56f-4f804d351def" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6f8a3567-fb55-488f-a6db-e2bb30775e05" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_92b58883-76cb-4307-a56f-4f804d351def" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_9c5145e2-ed36-4437-bdb2-af968b6ff08b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6f8a3567-fb55-488f-a6db-e2bb30775e05" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_9c5145e2-ed36-4437-bdb2-af968b6ff08b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_ad049711-05e4-4daf-b6ca-fe3cd3caea39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_6f8a3567-fb55-488f-a6db-e2bb30775e05" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_ad049711-05e4-4daf-b6ca-fe3cd3caea39" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/StockBasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#StockBasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/StockBasedCompensationNarrativeDetails" xlink:type="extended" id="i124fb43cbc0c49b7ba53c45f3796e3fb_StockBasedCompensationNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_aac8d5c7-8f9d-4ffa-ae05-aefa54c6bd35" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_aac8d5c7-8f9d-4ffa-ae05-aefa54c6bd35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_c23206cd-e58a-4cf6-9933-dd1f53cec904" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_c23206cd-e58a-4cf6-9933-dd1f53cec904" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_d63b9ce3-2fae-4f9c-a9c7-df8d3f168954" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_d63b9ce3-2fae-4f9c-a9c7-df8d3f168954" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_c2ea96a3-5cee-4108-b2c9-a7ed5f391b4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_c2ea96a3-5cee-4108-b2c9-a7ed5f391b4e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_c109c3a8-65ba-43ba-bcde-aefcd8b04261" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_c109c3a8-65ba-43ba-bcde-aefcd8b04261" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_60f3af3c-c168-443b-b921-9dbf048a3e73" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_60f3af3c-c168-443b-b921-9dbf048a3e73" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_83c98041-cd29-45ec-8477-d344063b47a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_83c98041-cd29-45ec-8477-d344063b47a3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97b98a98-2fd9-4580-9de5-1f9e558c6b03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_2d5aad55-abde-474f-9dbd-8a6d7f350d9f" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97b98a98-2fd9-4580-9de5-1f9e558c6b03" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_511150f0-0816-424f-9c58-a2d3ebd8ca2e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97b98a98-2fd9-4580-9de5-1f9e558c6b03" xlink:to="loc_srt_TitleOfIndividualAxis_511150f0-0816-424f-9c58-a2d3ebd8ca2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_511150f0-0816-424f-9c58-a2d3ebd8ca2e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_511150f0-0816-424f-9c58-a2d3ebd8ca2e" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_511150f0-0816-424f-9c58-a2d3ebd8ca2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_0fb20972-3927-40e1-a933-8f7ba53daed9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_511150f0-0816-424f-9c58-a2d3ebd8ca2e" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_0fb20972-3927-40e1-a933-8f7ba53daed9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_EmployeeMember_b166742e-d302-440d-9bd0-40ca552e1d5f" xlink:href="ucbi-20230331.xsd#ucbi_EmployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_0fb20972-3927-40e1-a933-8f7ba53daed9" xlink:to="loc_ucbi_EmployeeMember_b166742e-d302-440d-9bd0-40ca552e1d5f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_089bd7de-61db-43a1-ab06-8f19522a4020" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_0fb20972-3927-40e1-a933-8f7ba53daed9" xlink:to="loc_srt_DirectorMember_089bd7de-61db-43a1-ab06-8f19522a4020" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_3fb19080-4a63-45b7-a940-f919b1f98377" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97b98a98-2fd9-4580-9de5-1f9e558c6b03" xlink:to="loc_us-gaap_AwardTypeAxis_3fb19080-4a63-45b7-a940-f919b1f98377" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fb19080-4a63-45b7-a940-f919b1f98377_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_3fb19080-4a63-45b7-a940-f919b1f98377" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3fb19080-4a63-45b7-a940-f919b1f98377_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b60f3e0-2909-4e56-a400-4a2cd730ce16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_3fb19080-4a63-45b7-a940-f919b1f98377" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b60f3e0-2909-4e56-a400-4a2cd730ce16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_69517463-a85a-4f84-8871-21c1b8d84664" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b60f3e0-2909-4e56-a400-4a2cd730ce16" xlink:to="loc_us-gaap_EmployeeStockOptionMember_69517463-a85a-4f84-8871-21c1b8d84664" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_RestrictedStockUnitsRSUAndPerformanceStockUnitsMember_dbc97cc0-3566-4a74-a44e-e78761e531ce" xlink:href="ucbi-20230331.xsd#ucbi_RestrictedStockUnitsRSUAndPerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b60f3e0-2909-4e56-a400-4a2cd730ce16" xlink:to="loc_ucbi_RestrictedStockUnitsRSUAndPerformanceStockUnitsMember_dbc97cc0-3566-4a74-a44e-e78761e531ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_de2f94d6-4a71-40b6-8ab8-21b51d1a59d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97b98a98-2fd9-4580-9de5-1f9e558c6b03" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_de2f94d6-4a71-40b6-8ab8-21b51d1a59d9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_de2f94d6-4a71-40b6-8ab8-21b51d1a59d9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_de2f94d6-4a71-40b6-8ab8-21b51d1a59d9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_de2f94d6-4a71-40b6-8ab8-21b51d1a59d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_22b402ed-95e6-4ab8-9f25-472e59490fc2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_de2f94d6-4a71-40b6-8ab8-21b51d1a59d9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_22b402ed-95e6-4ab8-9f25-472e59490fc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_SalariesAndEmployeeBenefitExpenseMember_1c659001-a12e-4511-87c3-8abe4f71252a" xlink:href="ucbi-20230331.xsd#ucbi_SalariesAndEmployeeBenefitExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_22b402ed-95e6-4ab8-9f25-472e59490fc2" xlink:to="loc_ucbi_SalariesAndEmployeeBenefitExpenseMember_1c659001-a12e-4511-87c3-8abe4f71252a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_OtherOperatingExpenseMember_77dbde54-68f9-443d-b38c-3a6bc8a39686" xlink:href="ucbi-20230331.xsd#ucbi_OtherOperatingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_22b402ed-95e6-4ab8-9f25-472e59490fc2" xlink:to="loc_ucbi_OtherOperatingExpenseMember_77dbde54-68f9-443d-b38c-3a6bc8a39686" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/StockBasedCompensationRestrictedStockUnitsandOptionsOutstandingandActivityDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#StockBasedCompensationRestrictedStockUnitsandOptionsOutstandingandActivityDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/StockBasedCompensationRestrictedStockUnitsandOptionsOutstandingandActivityDetails" xlink:type="extended" id="i038372bfc42b4ea99bb8bb895bc689d0_StockBasedCompensationRestrictedStockUnitsandOptionsOutstandingandActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_625be7bb-9282-4422-b18c-bf4c7159522c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_RestrictedStockUnitsAbstract_510b5a03-ab3c-423b-ad32-55c10393048a" xlink:href="ucbi-20230331.xsd#ucbi_RestrictedStockUnitsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_625be7bb-9282-4422-b18c-bf4c7159522c" xlink:to="loc_ucbi_RestrictedStockUnitsAbstract_510b5a03-ab3c-423b-ad32-55c10393048a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9274fbae-5e13-4803-8a92-0c6994c13b15" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_RestrictedStockUnitsAbstract_510b5a03-ab3c-423b-ad32-55c10393048a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9274fbae-5e13-4803-8a92-0c6994c13b15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_cec16f80-80e5-452d-b3ee-db43d23fe208" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9274fbae-5e13-4803-8a92-0c6994c13b15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_cec16f80-80e5-452d-b3ee-db43d23fe208" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_bfe04fe5-d87e-4e32-bbc6-fcea31967713" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9274fbae-5e13-4803-8a92-0c6994c13b15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_bfe04fe5-d87e-4e32-bbc6-fcea31967713" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_a3aa7eb7-8b10-43e4-9d12-9039dbb56e69" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9274fbae-5e13-4803-8a92-0c6994c13b15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_a3aa7eb7-8b10-43e4-9d12-9039dbb56e69" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_5389997e-a60d-420f-82a7-5e93e3f9305c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9274fbae-5e13-4803-8a92-0c6994c13b15" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_5389997e-a60d-420f-82a7-5e93e3f9305c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1eb39cd3-57b0-4757-a93f-557c59d2f24a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber_d098801a-4c50-44d7-908c-008cec975f25" xlink:href="ucbi-20230331.xsd#ucbi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_RestrictedStockUnitsAbstract_510b5a03-ab3c-423b-ad32-55c10393048a" xlink:to="loc_ucbi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber_d098801a-4c50-44d7-908c-008cec975f25" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd4e8193-c854-4340-88d2-d0d885106a6d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_RestrictedStockUnitsAbstract_510b5a03-ab3c-423b-ad32-55c10393048a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd4e8193-c854-4340-88d2-d0d885106a6d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_718c60a6-2f48-4b35-84e6-a702eaa0ffc0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd4e8193-c854-4340-88d2-d0d885106a6d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_718c60a6-2f48-4b35-84e6-a702eaa0ffc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_fd6cc455-c06d-4b16-a09a-a8d2d8114156" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd4e8193-c854-4340-88d2-d0d885106a6d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_fd6cc455-c06d-4b16-a09a-a8d2d8114156" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_cd11a76c-91f5-427b-9929-beae222b5b51" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd4e8193-c854-4340-88d2-d0d885106a6d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_cd11a76c-91f5-427b-9929-beae222b5b51" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_5f57845f-f53d-4149-8c9a-a6a3513dafc0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_dd4e8193-c854-4340-88d2-d0d885106a6d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_5f57845f-f53d-4149-8c9a-a6a3513dafc0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_d4feac69-4d80-4eb4-86fd-ff2678c6143c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableWeightedAverageGrantDateFairValue_e6807724-f4fc-4049-a80e-79f43dda6988" xlink:href="ucbi-20230331.xsd#ucbi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_RestrictedStockUnitsAbstract_510b5a03-ab3c-423b-ad32-55c10393048a" xlink:to="loc_ucbi_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableWeightedAverageGrantDateFairValue_e6807724-f4fc-4049-a80e-79f43dda6988" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested_9affd16b-5b1b-4008-9412-37e1cb9b2e9b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_RestrictedStockUnitsAbstract_510b5a03-ab3c-423b-ad32-55c10393048a" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested_9affd16b-5b1b-4008-9412-37e1cb9b2e9b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding_172a1be4-6da8-4c0a-9cf9-ec0a46f4ce7b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_RestrictedStockUnitsAbstract_510b5a03-ab3c-423b-ad32-55c10393048a" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding_172a1be4-6da8-4c0a-9cf9-ec0a46f4ce7b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:href="ucbi-20230331.xsd#ucbi_StockOptionsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_625be7bb-9282-4422-b18c-bf4c7159522c" xlink:to="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_cd2ae638-9040-4729-8850-b44731a9da2b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_cd2ae638-9040-4729-8850-b44731a9da2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_0efed90f-bd08-4553-9360-35afdf49cb18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_cd2ae638-9040-4729-8850-b44731a9da2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_0efed90f-bd08-4553-9360-35afdf49cb18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_a010d72b-3a5e-4405-8dcd-72d5259ecbca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_cd2ae638-9040-4729-8850-b44731a9da2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_a010d72b-3a5e-4405-8dcd-72d5259ecbca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_fb1d2188-f8c1-4a93-bd82-a507c3a5704a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_cd2ae638-9040-4729-8850-b44731a9da2b" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_fb1d2188-f8c1-4a93-bd82-a507c3a5704a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_4b653e7e-dbb8-4ded-9ddf-b4bea7f805a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_cd2ae638-9040-4729-8850-b44731a9da2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_4b653e7e-dbb8-4ded-9ddf-b4bea7f805a7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_28664f11-9bff-4616-9017-59d1d9875432" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_59d13486-d5ef-4d93-9e04-37533b514da7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_59d13486-d5ef-4d93-9e04-37533b514da7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_eb5f7d6b-ebed-442e-a969-466f279ecc98" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_eb5f7d6b-ebed-442e-a969-466f279ecc98" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_c4d09bbe-ef0d-4c3a-a6fc-ab927827243c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_eb5f7d6b-ebed-442e-a969-466f279ecc98" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_c4d09bbe-ef0d-4c3a-a6fc-ab927827243c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_0d99cdb7-e6a7-4a78-969e-624d18d32c83" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_eb5f7d6b-ebed-442e-a969-466f279ecc98" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_0d99cdb7-e6a7-4a78-969e-624d18d32c83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_7e5e1f00-3ba9-4ed2-b656-f7a0a4b96716" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_eb5f7d6b-ebed-442e-a969-466f279ecc98" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_7e5e1f00-3ba9-4ed2-b656-f7a0a4b96716" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_0ac88832-4aee-4f9a-b98e-ffc6a311ac7c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_eb5f7d6b-ebed-442e-a969-466f279ecc98" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_0ac88832-4aee-4f9a-b98e-ffc6a311ac7c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_b0d9a9c4-1619-4973-aaee-bd846e8a0b2d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_d355aefd-7e2d-4ccd-a609-4b347eb4d4d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_d355aefd-7e2d-4ccd-a609-4b347eb4d4d0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_95519ffb-7f31-4423-b83f-9d0eb767a00f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_95519ffb-7f31-4423-b83f-9d0eb767a00f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_86269f96-97a1-4606-8990-24af5ad043e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_86269f96-97a1-4606-8990-24af5ad043e6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_caa7d307-e24f-4f88-8d1a-1dad1b767dbd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_caa7d307-e24f-4f88-8d1a-1dad1b767dbd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_f11dec5b-be1a-4a8a-89ab-cc7063d5d83f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_f11dec5b-be1a-4a8a-89ab-cc7063d5d83f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_f1e7e4c9-33cd-474a-9cb5-cd287ca318a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ucbi_StockOptionsAbstract_5fef15d7-6d3d-481f-b57f-9f71a7dc2c14" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_f1e7e4c9-33cd-474a-9cb5-cd287ca318a1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_59e71c40-f318-47fa-ac96-2614bc9712ce" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_625be7bb-9282-4422-b18c-bf4c7159522c" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_59e71c40-f318-47fa-ac96-2614bc9712ce" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_0752fb14-6672-4872-9897-6e3b493ab11a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_59e71c40-f318-47fa-ac96-2614bc9712ce" xlink:to="loc_us-gaap_AwardTypeAxis_0752fb14-6672-4872-9897-6e3b493ab11a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0752fb14-6672-4872-9897-6e3b493ab11a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0752fb14-6672-4872-9897-6e3b493ab11a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0752fb14-6672-4872-9897-6e3b493ab11a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_15ee8bc4-5931-4c46-b209-96c50912fba4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0752fb14-6672-4872-9897-6e3b493ab11a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_15ee8bc4-5931-4c46-b209-96c50912fba4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_dda72316-a8bc-4a36-9985-2798bacff759" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_15ee8bc4-5931-4c46-b209-96c50912fba4" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_dda72316-a8bc-4a36-9985-2798bacff759" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/ReclassificationsOutofAOCIDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#ReclassificationsOutofAOCIDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/ReclassificationsOutofAOCIDetails" xlink:type="extended" id="idc5c338e16bb41efa314be2192fff64e_ReclassificationsOutofAOCIDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_425b98a2-2c8e-4e9d-b14c-867251cb5363" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_425b98a2-2c8e-4e9d-b14c-867251cb5363" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_b2574298-447e-4e90-aa06-c4cc0aed9985" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_b2574298-447e-4e90-aa06-c4cc0aed9985" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndDividendIncomeOperating_c2e0c5ea-7338-497e-b889-55abe2d46e9b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestAndDividendIncomeOperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_InterestAndDividendIncomeOperating_c2e0c5ea-7338-497e-b889-55abe2d46e9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseLongTermDebt_23625077-7eff-45d0-8df4-9cdf0f62cf9d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_InterestExpenseLongTermDebt_23625077-7eff-45d0-8df4-9cdf0f62cf9d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LaborAndRelatedExpense_492bf1f2-58cf-4b5b-8c83-9aa17e91e596" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LaborAndRelatedExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_LaborAndRelatedExpense_492bf1f2-58cf-4b5b-8c83-9aa17e91e596" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoninterestExpense_8755768a-f6fa-4075-8956-0a73ef822ea9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNoninterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_OtherNoninterestExpense_8755768a-f6fa-4075-8956-0a73ef822ea9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e3481b8a-2986-4cfe-8bad-dc06c865e3b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e3481b8a-2986-4cfe-8bad-dc06c865e3b5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_7563c539-694e-4c2f-bc60-a9789fd3a8fb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_NetIncomeLoss_7563c539-694e-4c2f-bc60-a9789fd3a8fb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_477cdcea-d6c7-4034-a7c4-d349702ba92c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_3a3167d0-8c57-44d9-82e5-73e41300f528" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_477cdcea-d6c7-4034-a7c4-d349702ba92c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_b3532814-705b-436b-b740-27edba722393" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_477cdcea-d6c7-4034-a7c4-d349702ba92c" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_b3532814-705b-436b-b740-27edba722393" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_b3532814-705b-436b-b740-27edba722393_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_b3532814-705b-436b-b740-27edba722393" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_b3532814-705b-436b-b740-27edba722393_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_a1e57a7d-01cc-43fb-80b7-b81b00e93189" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_b3532814-705b-436b-b740-27edba722393" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_a1e57a7d-01cc-43fb-80b7-b81b00e93189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_8ad2f82a-a59f-4dda-a839-346f2cc746a8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_a1e57a7d-01cc-43fb-80b7-b81b00e93189" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_8ad2f82a-a59f-4dda-a839-346f2cc746a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_757fb897-6b7f-4184-8cdd-e3cb45554db3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_477cdcea-d6c7-4034-a7c4-d349702ba92c" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_757fb897-6b7f-4184-8cdd-e3cb45554db3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_757fb897-6b7f-4184-8cdd-e3cb45554db3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_757fb897-6b7f-4184-8cdd-e3cb45554db3" xlink:to="loc_us-gaap_EquityComponentDomain_757fb897-6b7f-4184-8cdd-e3cb45554db3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_3d6bc505-8c83-43c1-beec-d6b8e95b2e31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_757fb897-6b7f-4184-8cdd-e3cb45554db3" xlink:to="loc_us-gaap_EquityComponentDomain_3d6bc505-8c83-43c1-beec-d6b8e95b2e31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_2d649243-5e24-4a87-a09b-1abcdbfa5720" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3d6bc505-8c83-43c1-beec-d6b8e95b2e31" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_2d649243-5e24-4a87-a09b-1abcdbfa5720" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_AccumulatedAmortizationOfLossesIncludedInNetIncomeOnAvailableForSaleSecuritiesTransferredToHeldToMaturityMember_c9c73059-df13-4418-a225-e91772fcc690" xlink:href="ucbi-20230331.xsd#ucbi_AccumulatedAmortizationOfLossesIncludedInNetIncomeOnAvailableForSaleSecuritiesTransferredToHeldToMaturityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3d6bc505-8c83-43c1-beec-d6b8e95b2e31" xlink:to="loc_ucbi_AccumulatedAmortizationOfLossesIncludedInNetIncomeOnAvailableForSaleSecuritiesTransferredToHeldToMaturityMember_c9c73059-df13-4418-a225-e91772fcc690" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_f21574db-54b9-438b-8d08-12a5a65cd4ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3d6bc505-8c83-43c1-beec-d6b8e95b2e31" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_f21574db-54b9-438b-8d08-12a5a65cd4ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_8e6c08cf-c769-4183-9674-8380ff254bad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3d6bc505-8c83-43c1-beec-d6b8e95b2e31" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_8e6c08cf-c769-4183-9674-8380ff254bad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_38a27466-91dd-47a8-86bb-9fe5c3f9c18a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_8e6c08cf-c769-4183-9674-8380ff254bad" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_38a27466-91dd-47a8-86bb-9fe5c3f9c18a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_6fc1b8c5-3541-4024-9da5-799bfbc07da0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_8e6c08cf-c769-4183-9674-8380ff254bad" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_6fc1b8c5-3541-4024-9da5-799bfbc07da0" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/EarningsPerShareComputationofBasicandDilutedEarningsPerShareDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#EarningsPerShareComputationofBasicandDilutedEarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/EarningsPerShareComputationofBasicandDilutedEarningsPerShareDetails" xlink:type="extended" id="i719afeb6bc02474e89e8b9fe6f4eeef7_EarningsPerShareComputationofBasicandDilutedEarningsPerShareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedLineItems_6d285ec7-9778-4d63-baf9-a0e3e3300431" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDilutedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_6d285ec7-9778-4d63-baf9-a0e3e3300431" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_ed96fdf4-0eaa-4a3d-b95a-c46d6900f2f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:to="loc_us-gaap_NetIncomeLoss_ed96fdf4-0eaa-4a3d-b95a-c46d6900f2f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_9822da79-4aa7-4e6d-9547-7395f09eb856" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockDividendsIncomeStatementImpact"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:to="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_9822da79-4aa7-4e6d-9547-7395f09eb856" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic_a47fb5a0-657c-4766-b0e3-d15489ecdea4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:to="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic_a47fb5a0-657c-4766-b0e3-d15489ecdea4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_0ac0459b-0e0f-4879-bd7e-6cc7392939ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_0ac0459b-0e0f-4879-bd7e-6cc7392939ee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_645dc5db-67c4-48a6-9f39-29d6a880b905" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_645dc5db-67c4-48a6-9f39-29d6a880b905" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_b0828516-2baa-4b9b-a5b6-c2dd68693937" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_b0828516-2baa-4b9b-a5b6-c2dd68693937" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_ce6a6e14-29d9-4353-9b48-b23c77cc36f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_b0828516-2baa-4b9b-a5b6-c2dd68693937" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_ce6a6e14-29d9-4353-9b48-b23c77cc36f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DilutiveSecuritiesAbstract_038e516c-b09e-4bb1-a461-31cd78cd96d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DilutiveSecuritiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_b0828516-2baa-4b9b-a5b6-c2dd68693937" xlink:to="loc_us-gaap_DilutiveSecuritiesAbstract_038e516c-b09e-4bb1-a461-31cd78cd96d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_fe2bd9f6-54ab-49df-a74c-73de343d8779" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DilutiveSecuritiesAbstract_038e516c-b09e-4bb1-a461-31cd78cd96d9" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_fe2bd9f6-54ab-49df-a74c-73de343d8779" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_cae62c38-a6b4-40be-b603-3c9f4ab7f541" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_b0828516-2baa-4b9b-a5b6-c2dd68693937" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_cae62c38-a6b4-40be-b603-3c9f4ab7f541" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_5c13154d-7814-4427-9c0d-4ce2d158e789" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_57a59174-ad52-4804-a3aa-ef24bddc24da" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_5c13154d-7814-4427-9c0d-4ce2d158e789" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_1207edfe-5418-4c42-9207-3f8ffaed854a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_5c13154d-7814-4427-9c0d-4ce2d158e789" xlink:to="loc_us-gaap_EarningsPerShareBasic_1207edfe-5418-4c42-9207-3f8ffaed854a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_843cf63a-6dce-4aa8-aef0-83df085e849f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_5c13154d-7814-4427-9c0d-4ce2d158e789" xlink:to="loc_us-gaap_EarningsPerShareDiluted_843cf63a-6dce-4aa8-aef0-83df085e849f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_d0b1f545-533f-4f0f-9519-99cdf4a6461e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_6d285ec7-9778-4d63-baf9-a0e3e3300431" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_d0b1f545-533f-4f0f-9519-99cdf4a6461e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_25fc05e9-5ee4-42d4-af74-12f99e36b0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_d0b1f545-533f-4f0f-9519-99cdf4a6461e" xlink:to="loc_us-gaap_AwardTypeAxis_25fc05e9-5ee4-42d4-af74-12f99e36b0bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25fc05e9-5ee4-42d4-af74-12f99e36b0bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_25fc05e9-5ee4-42d4-af74-12f99e36b0bb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25fc05e9-5ee4-42d4-af74-12f99e36b0bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e992d08d-c99b-4a41-ab23-32993a5c7cdf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_25fc05e9-5ee4-42d4-af74-12f99e36b0bb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e992d08d-c99b-4a41-ab23-32993a5c7cdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_ce9a7e88-f23c-4b0e-b62c-b1c5f7cc0385" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e992d08d-c99b-4a41-ab23-32993a5c7cdf" xlink:to="loc_us-gaap_EmployeeStockOptionMember_ce9a7e88-f23c-4b0e-b62c-b1c5f7cc0385" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_d21db57d-a1fa-4b16-ac42-fa093e8d9b38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e992d08d-c99b-4a41-ab23-32993a5c7cdf" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_d21db57d-a1fa-4b16-ac42-fa093e8d9b38" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/RegulatoryMattersDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#RegulatoryMattersDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/RegulatoryMattersDetails" xlink:type="extended" id="idad7cc7c0a9841628f20b6d65e241655_RegulatoryMattersDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankingRegulationCommonEquityTierOneRiskBasedCapitalRatioCapitalAdequacyMinimum_ea775d4f-b41c-4cb6-bb3b-7abe576aa506" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BankingRegulationCommonEquityTierOneRiskBasedCapitalRatioCapitalAdequacyMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_BankingRegulationCommonEquityTierOneRiskBasedCapitalRatioCapitalAdequacyMinimum_ea775d4f-b41c-4cb6-bb3b-7abe576aa506" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankingRegulationCommonEquityTierOneRiskBasedCapitalRatioWellCapitalizedMinimum_73a98a8d-e631-4726-8a2d-b2563d749f21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BankingRegulationCommonEquityTierOneRiskBasedCapitalRatioWellCapitalizedMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_BankingRegulationCommonEquityTierOneRiskBasedCapitalRatioWellCapitalizedMinimum_73a98a8d-e631-4726-8a2d-b2563d749f21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonEquityTierOneCapitalRatio_942201cd-2e31-4c36-93a3-510475272841" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonEquityTierOneCapitalRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_CommonEquityTierOneCapitalRatio_942201cd-2e31-4c36-93a3-510475272841" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets_8f3a2cc6-f551-4872-a771-209d70dea05e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets_8f3a2cc6-f551-4872-a771-209d70dea05e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets_7ae20bfb-ffc6-4b35-a136-372b1075e481" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets_7ae20bfb-ffc6-4b35-a136-372b1075e481" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets_2e00ca4b-00ae-4b9f-bb51-d6fd066812dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets_2e00ca4b-00ae-4b9f-bb51-d6fd066812dc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets_e7cd2917-7cc7-4464-950c-aca0286fb8cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets_e7cd2917-7cc7-4464-950c-aca0286fb8cd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets_9ea0910a-5384-40b1-9d1a-9d5040d54770" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets_9ea0910a-5384-40b1-9d1a-9d5040d54770" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalToRiskWeightedAssets_a859a036-29f0-4b01-bb5a-8903f415b6bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalToRiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_CapitalToRiskWeightedAssets_a859a036-29f0-4b01-bb5a-8903f415b6bf" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets_68cfa598-ac01-4837-b619-563b779284eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets_68cfa598-ac01-4837-b619-563b779284eb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets_272da653-28f2-4e21-afaf-1cada8396c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets_272da653-28f2-4e21-afaf-1cada8396c4f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneLeverageCapitalToAverageAssets_109693e8-ccaa-4ba4-9f9c-925965836a95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TierOneLeverageCapitalToAverageAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_TierOneLeverageCapitalToAverageAssets_109693e8-ccaa-4ba4-9f9c-925965836a95" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonEquityTierOneCapital_5f1e571a-c7d6-4e91-872b-ddaa2853b0bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonEquityTierOneCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_CommonEquityTierOneCapital_5f1e571a-c7d6-4e91-872b-ddaa2853b0bf" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TierOneRiskBasedCapital_b41f5d82-953b-4404-9bf9-4302e255008b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TierOneRiskBasedCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_TierOneRiskBasedCapital_b41f5d82-953b-4404-9bf9-4302e255008b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Capital_16fb2a1f-c086-4272-9802-667bb4ab8247" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Capital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_Capital_16fb2a1f-c086-4272-9802-667bb4ab8247" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RiskWeightedAssets_56c619e5-88d1-4866-9736-afc8f71e8ecf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RiskWeightedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_RiskWeightedAssets_56c619e5-88d1-4866-9736-afc8f71e8ecf" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_7ca25e5d-896d-44dd-a218-526f0060ae49" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RegulatoryAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_RegulatoryAssets_7ca25e5d-896d-44dd-a218-526f0060ae49" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_e00407a3-aa8e-4ae3-a4d1-67b22cc550b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsLineItems_1cfda94c-de6b-4386-ad91-e87aadb78e37" xlink:to="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_e00407a3-aa8e-4ae3-a4d1-67b22cc550b5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_1177beb7-e49a-46cd-941f-5a5886302fe6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfComplianceWithRegulatoryCapitalRequirementsUnderBankingRegulationsTable_e00407a3-aa8e-4ae3-a4d1-67b22cc550b5" xlink:to="loc_srt_ConsolidatedEntitiesAxis_1177beb7-e49a-46cd-941f-5a5886302fe6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_1177beb7-e49a-46cd-941f-5a5886302fe6_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_1177beb7-e49a-46cd-941f-5a5886302fe6" xlink:to="loc_srt_ConsolidatedEntitiesDomain_1177beb7-e49a-46cd-941f-5a5886302fe6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_cd1d2182-3863-4673-b9cd-a9e1a7a3e6a5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_1177beb7-e49a-46cd-941f-5a5886302fe6" xlink:to="loc_srt_ConsolidatedEntitiesDomain_cd1d2182-3863-4673-b9cd-a9e1a7a3e6a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SubsidiariesMember_c87039ce-3ae9-486a-96ee-654d1d6a0322" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SubsidiariesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_cd1d2182-3863-4673-b9cd-a9e1a7a3e6a5" xlink:to="loc_srt_SubsidiariesMember_c87039ce-3ae9-486a-96ee-654d1d6a0322" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/CommitmentsandContingenciesContractualAmountofOffbalanceSheetInstrumentsDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#CommitmentsandContingenciesContractualAmountofOffbalanceSheetInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/CommitmentsandContingenciesContractualAmountofOffbalanceSheetInstrumentsDetails" xlink:type="extended" id="ia988b978217b48639346438cf2128ed4_CommitmentsandContingenciesContractualAmountofOffbalanceSheetInstrumentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOffBalanceSheetRisksDisclosureInformationLineItems_727fdd54-ca18-4124-8c2b-fba22da61c2b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueOffBalanceSheetRisksDisclosureInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnusedCommitmentsToExtendCredit_7f2a1606-fc79-4206-8201-6504eee32420" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnusedCommitmentsToExtendCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueOffBalanceSheetRisksDisclosureInformationLineItems_727fdd54-ca18-4124-8c2b-fba22da61c2b" xlink:to="loc_us-gaap_UnusedCommitmentsToExtendCredit_7f2a1606-fc79-4206-8201-6504eee32420" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFairValueOffBalanceSheetRisksTable_2c0dc786-de41-45f1-92c8-ee95d440f74c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFairValueOffBalanceSheetRisksTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueOffBalanceSheetRisksDisclosureInformationLineItems_727fdd54-ca18-4124-8c2b-fba22da61c2b" xlink:to="loc_us-gaap_ScheduleOfFairValueOffBalanceSheetRisksTable_2c0dc786-de41-45f1-92c8-ee95d440f74c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_7f9c252c-79ef-4e1a-85a8-bd25040beb40" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFairValueOffBalanceSheetRisksTable_2c0dc786-de41-45f1-92c8-ee95d440f74c" xlink:to="loc_us-gaap_FinancialInstrumentAxis_7f9c252c-79ef-4e1a-85a8-bd25040beb40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7f9c252c-79ef-4e1a-85a8-bd25040beb40_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7f9c252c-79ef-4e1a-85a8-bd25040beb40" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_7f9c252c-79ef-4e1a-85a8-bd25040beb40_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_47e14d66-b397-4ec6-a55e-637e30b70d82" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_7f9c252c-79ef-4e1a-85a8-bd25040beb40" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_47e14d66-b397-4ec6-a55e-637e30b70d82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsToExtendCreditMember_bf295946-c2bf-4697-8b1d-631fb8e7b6d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsToExtendCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_47e14d66-b397-4ec6-a55e-637e30b70d82" xlink:to="loc_us-gaap_CommitmentsToExtendCreditMember_bf295946-c2bf-4697-8b1d-631fb8e7b6d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_64a7108f-d0a4-45db-a4ee-0f24f1b04aef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_47e14d66-b397-4ec6-a55e-637e30b70d82" xlink:to="loc_us-gaap_LetterOfCreditMember_64a7108f-d0a4-45db-a4ee-0f24f1b04aef" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ucbi.com/role/CommitmentandContingenciesTaxCreditandCertainEquityMethodInvestmentsDetails" xlink:type="simple" xlink:href="ucbi-20230331.xsd#CommitmentandContingenciesTaxCreditandCertainEquityMethodInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://ucbi.com/role/CommitmentandContingenciesTaxCreditandCertainEquityMethodInvestmentsDetails" xlink:type="extended" id="i405411d11dd84957b4122787a8959fc9_CommitmentandContingenciesTaxCreditandCertainEquityMethodInvestmentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_23dcf1c2-9c3b-40b6-a3a7-5dfc46ae88f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestments_0d9f416f-91fa-4c83-bb82-e78c8270199a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_23dcf1c2-9c3b-40b6-a3a7-5dfc46ae88f3" xlink:to="loc_us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestments_0d9f416f-91fa-4c83-bb82-e78c8270199a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_QualifiedAffordableHousingProjectInvestmentsCommitment_714ee613-9a43-4c39-b159-720303fa15fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_QualifiedAffordableHousingProjectInvestmentsCommitment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_23dcf1c2-9c3b-40b6-a3a7-5dfc46ae88f3" xlink:to="loc_us-gaap_QualifiedAffordableHousingProjectInvestmentsCommitment_714ee613-9a43-4c39-b159-720303fa15fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_14c86532-c79e-44e3-87c3-b9a37b2914a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_23dcf1c2-9c3b-40b6-a3a7-5dfc46ae88f3" xlink:to="loc_us-gaap_EquityMethodInvestments_14c86532-c79e-44e3-87c3-b9a37b2914a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitment_4a7b913f-f1cd-4b9a-9a3c-4fcaaceff87d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_23dcf1c2-9c3b-40b6-a3a7-5dfc46ae88f3" xlink:to="loc_us-gaap_OtherCommitment_4a7b913f-f1cd-4b9a-9a3c-4fcaaceff87d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_7a349b80-0986-4d13-9df3-a2d79d23b0f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_23dcf1c2-9c3b-40b6-a3a7-5dfc46ae88f3" xlink:to="loc_us-gaap_OtherCommitmentsTable_7a349b80-0986-4d13-9df3-a2d79d23b0f8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_1b064436-d3ed-4dca-acb1-f4c433bf7648" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_7a349b80-0986-4d13-9df3-a2d79d23b0f8" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_1b064436-d3ed-4dca-acb1-f4c433bf7648" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_1b064436-d3ed-4dca-acb1-f4c433bf7648_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_1b064436-d3ed-4dca-acb1-f4c433bf7648" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_1b064436-d3ed-4dca-acb1-f4c433bf7648_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_594749e9-8ceb-445b-998d-f21179bfe858" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_1b064436-d3ed-4dca-acb1-f4c433bf7648" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_594749e9-8ceb-445b-998d-f21179bfe858" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsMember_97c88eb5-f21c-4044-875f-2a15f0d11faf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_594749e9-8ceb-445b-998d-f21179bfe858" xlink:to="loc_us-gaap_OtherAssetsMember_97c88eb5-f21c-4044-875f-2a15f0d11faf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesMember_e11ff9f3-9659-4012-abaa-d11db36642c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_594749e9-8ceb-445b-998d-f21179bfe858" xlink:to="loc_us-gaap_OtherLiabilitiesMember_e11ff9f3-9659-4012-abaa-d11db36642c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8e131a4b-723a-4957-b113-8631114d003f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_7a349b80-0986-4d13-9df3-a2d79d23b0f8" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8e131a4b-723a-4957-b113-8631114d003f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_8e131a4b-723a-4957-b113-8631114d003f_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8e131a4b-723a-4957-b113-8631114d003f" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_8e131a4b-723a-4957-b113-8631114d003f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_89d2f1bb-e3d1-497a-816f-c8bc12ded480" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8e131a4b-723a-4957-b113-8631114d003f" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_89d2f1bb-e3d1-497a-816f-c8bc12ded480" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_InvestmentsInLIHTCMember_978d100c-eda5-43dc-b921-c4aeeb691f4d" xlink:href="ucbi-20230331.xsd#ucbi_InvestmentsInLIHTCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_89d2f1bb-e3d1-497a-816f-c8bc12ded480" xlink:to="loc_ucbi_InvestmentsInLIHTCMember_978d100c-eda5-43dc-b921-c4aeeb691f4d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_RenewableEnergyInvestmentsMember_6761894c-7982-496b-b6d4-ce242cc5c11d" xlink:href="ucbi-20230331.xsd#ucbi_RenewableEnergyInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_89d2f1bb-e3d1-497a-816f-c8bc12ded480" xlink:to="loc_ucbi_RenewableEnergyInvestmentsMember_6761894c-7982-496b-b6d4-ce242cc5c11d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ucbi_FintechFundsMember_f8f4e3fa-7d1d-4e7d-bb80-1eb907d73d74" xlink:href="ucbi-20230331.xsd#ucbi_FintechFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_89d2f1bb-e3d1-497a-816f-c8bc12ded480" xlink:to="loc_ucbi_FintechFundsMember_f8f4e3fa-7d1d-4e7d-bb80-1eb907d73d74" xlink:type="arc" order="2"/>
  </link:definitionLink>
</link:linkbase>
