The Collaborative International Dictionary of English v.0.48:

Beau monde \Beau` monde"\ [F. beau fine + monde world.]
   The fashionable world; people of fashion and gayety. --Prior.
   [1913 Webster]

WordNet (r) 3.0 (2006):

beau monde
    n 1: the fashionable elite [syn: society, high society,
         beau monde, smart set, bon ton]