Billionaire rhymes with:
millionaire, multimillionaire, millionaire, multimillionaire, millionaire, multimillionaire, concessionaire, debonair, doctrinaire, millionaire, multimillionaire, nationair, questionnaire
Billionaire sounds like:
ballmer, balmer, bayliner, bellemare, bellmore, belmore, billmeyer, bloemer, bloomer, blumer, bulmer