Betterment rhymes with:
accouterment, accoutrement, accouterment, accoutrement, antigovernment, bewilderment, dismemberment, empowerment, endangerment, government, measurement, postretirement, retirement, wonderment
accouterment, accoutrement, accouterment, accoutrement, antigovernment, bewilderment, dismemberment, empowerment, endangerment, government, measurement, postretirement, retirement, wonderment