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multimillionaire vs. millionaire

multimillionaire
[muhl-tee-mil-yuh-nair, muhl-tahy-] / ˌmʌl tiˌmɪl jəˈnɛər, ˌmʌl taɪ- /

noun

  1. a person who possesses a fortune that amounts to many millions of dollars, euros, etc.

millionaire
[mil-yuh-nair] / ˌmɪl jəˈnɛər /
Or millionnaire

noun

millionaires plural

  1. a person whose wealth amounts to a million or more in some unit of currency, as dollars.

  2. any very rich person.