The Collaborative International Dictionary of English v.0.48:

Nouveau riche \Nou`veau" riche"\, m., Nouvelle riche \Nou`velle"
riche"\, f.; pl. m. Noveaux riches, f. Nouvelles riches.
   [F.]
   A person newly rich. Contrasted with old money.
   [Webster 1913 Suppl. +PJC]