The Collaborative International Dictionary of English v.0.48:

Poseur \Po`seur"\, n. masc.; pl. Poseurs, Poseuse \Po`seuse"\,
   n. fem.; pl. Poseuses, [F.]
   A person who poses or attitudizes, esp. mentally.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

poseuse
    n 1: a woman poseur