Definition of billionaire noun from the Oxford Advanced Learner's Dictionary

 

billionaire

 noun
noun
BrE BrE//ˌbɪljəˈneə(r)//
 
; NAmE NAmE//ˌbɪljəˈner//
 
 
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an extremely rich person, who has at least a thousand million pounds, dollars, etc. in money or property a Texas billionaire Word Origin mid 19th cent.: from billion, on the pattern of millionaire.
See the Oxford Advanced American Dictionary entry: billionaire