The Collaborative International Dictionary of English v.0.48:

geisha \gei"sha\ (g[=a]"sh[.a]), n.; pl. geisha
   (g[=a]"sh[.a]), Geishas (g[=a]"sh[.a]z). [Jap., art
   person.]
   A Japanese singing and dancing girl, trained to provide
   entertainment and company for a man or group of men.
   [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

geisha
    n 1: a Japanese woman trained to entertain men with conversation
         and singing and dancing [syn: geisha, geisha girl]