<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by Broadridge Transform (tm) - http://www.broadridge.com -->
<!-- Created: Tue Aug 18 10:23:57 UTC 2026 -->
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:xbrldt="http://xbrl.org/2005/xbrldt">
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#SeriesOnly" roleURI="http://xbrl.sec.gov/oef/role/SeriesOnly"/>
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#ClassOnly" roleURI="http://xbrl.sec.gov/oef/role/ClassOnly"/>
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#RiskOnly" roleURI="http://xbrl.sec.gov/rr/role/RiskOnly"/>
  <roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#PerformanceMeasureOnly" roleURI="http://xbrl.sec.gov/rr/role/PerformanceMeasureOnly"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member"/>
  <arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all"/>
  <definitionLink xlink:role="http://xbrl.sec.gov/oef/role/SeriesOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="dei_EntityDomain" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_S000039110Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_S000039110Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="ck0001553195_S000039110Member" order="11" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:role="http://xbrl.sec.gov/oef/role/ClassOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="oef_ShareClassDomain" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_ShareClassDomain"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120242Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120242Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120242Member" order="11" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120254Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120254Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120254Member" order="12" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120251Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120251Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120251Member" order="13" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120256Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120256Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120256Member" order="14" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120257Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120257Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120257Member" order="15" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120252Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120252Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120252Member" order="16" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120253Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120253Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120253Member" order="17" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000179949Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000179949Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000179949Member" order="18" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000222346Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000222346Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000222346Member" order="19" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000222347Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000222347Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000222347Member" order="20" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120244Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120244Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120244Member" order="21" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120245Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120245Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120245Member" order="22" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120246Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120246Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120246Member" order="23" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120247Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120247Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120247Member" order="24" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120248Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120248Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120248Member" order="25" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000120249Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000120249Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000120249Member" order="26" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000148464Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000148464Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000148464Member" order="27" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_C000164799Member" xlink:href="ck0001553195-20260831.xsd#ck0001553195_C000164799Member"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_ShareClassDomain" xlink:to="ck0001553195_C000164799Member" order="28" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:role="http://xbrl.sec.gov/rr/role/RiskOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="oef_AllRisksMember" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_AllRisksMember"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_MarketConditionsMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_MarketConditionsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="ck0001553195_MarketConditionsMember" order="11" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_IssuerRisksMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_IssuerRisksMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="ck0001553195_IssuerRisksMember" order="12" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_InvestingInDebtInstrumentsMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_InvestingInDebtInstrumentsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="ck0001553195_InvestingInDebtInstrumentsMember" order="13" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_InvestingInSecuritiesBackedByTheUSGovernmentMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_InvestingInSecuritiesBackedByTheUSGovernmentMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="ck0001553195_InvestingInSecuritiesBackedByTheUSGovernmentMember" order="14" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_InvestingInDerivativesMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_InvestingInDerivativesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="ck0001553195_InvestingInDerivativesMember" order="15" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_LiquidityRiskMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_LiquidityRiskMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="ck0001553195_LiquidityRiskMember" order="16" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_InvestingOutsideTheUnitedStatesMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_InvestingOutsideTheUnitedStatesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="ck0001553195_InvestingOutsideTheUnitedStatesMember" order="17" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_InvestingInEmergingMarketsMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_InvestingInEmergingMarketsMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="ck0001553195_InvestingInEmergingMarketsMember" order="18" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="srt_ManagementMember" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ManagementMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="srt_ManagementMember" order="19" xbrldt:closed="true"/>
  </definitionLink>
  <definitionLink xlink:role="http://xbrl.sec.gov/rr/role/PerformanceMeasureOnly" xlink:type="extended">
    <loc xlink:type="locator" xlink:label="oef_PerformanceMeasureDomain" xlink:href="https://xbrl.sec.gov/oef/2026/oef-2026.xsd#oef_PerformanceMeasureDomain"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_index_Bloomberg_US_Aggregate_Index_reflects_no_deductions_for_sales_charges_account_fees_expenses_or_US_federal_income_taxesMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_index_Bloomberg_US_Aggregate_Index_reflects_no_deductions_for_sales_charges_account_fees_expenses_or_US_federal_income_taxesMember"/>
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_PerformanceMeasureDomain" xlink:to="ck0001553195_index_Bloomberg_US_Aggregate_Index_reflects_no_deductions_for_sales_charges_account_fees_expenses_or_US_federal_income_taxesMember" order="11" xbrldt:closed="true"/>
    <loc xlink:type="locator" xlink:label="ck0001553195_index_Bloomberg_US_Corporate_Investment_Grade_Index_reflects_no_deductions_for_sales_charges_account_fees_expenses_or_US_federal_income_taxesMember" xlink:href="ck0001553195-20260831.xsd#ck0001553195_index_Bloomberg_US_Corporate_Investment_Grade_Index_reflects_no_deductions_for_sales_charges_account_fees_expenses_or_US_federal_income_taxesMember"/>
<!-- [WMV7][kUh9HNii/AsgqFbvrd5fPGRqS8Tc7B9Wy0OpEFuHLt5Rno4RdmscB5MarrdhQDeh08V4NriYgLwHx8TUpka6FM1mXLJy59w69kw4My6zyD0BcY+uvDe276fXbB2ZGY0MCLDV5HDL638ubV8goGsDzGSxn1F9ZR/OzSaWy+JJXHKwUkYZ0mOXpXEFruCaZR9HdHqlTupTEriltFVbswZllJFCE53YSpfz21fDPSh0pI/+2qWUZUOLveoQ3vi10yIxyFIrNXn3vlmnrZx+Q92BAWFC/H8v+cvpUYwqQ1NAnCg3p5Ze7k53BnjE6O+nSoC3I3Vvwn+7IiDl6Kxp5Sa0+DT89kLntzt5CEh5ZJVDvbgo342O42CefUcYs+Bw64q8hLs1YU7UwvM=] CSR-->
    <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_PerformanceMeasureDomain" xlink:to="ck0001553195_index_Bloomberg_US_Corporate_Investment_Grade_Index_reflects_no_deductions_for_sales_charges_account_fees_expenses_or_US_federal_income_taxesMember" order="12" xbrldt:closed="true"/>
  </definitionLink>
</linkbase>
