The Collaborative International Dictionary of English v.0.48:

gigolo \gig"o*lo\ (j[i^]g"[.a]*l[=o]), n.
   A man whose main income is derived from gifts or payments
   from women in return for his sexual favors or companionship.
   [PJC]

   2. A professional male escort or dancing partner. --RHUD
      [PJC] Gigot

WordNet (r) 3.0 (2006):

gigolo
    n 1: a man who has sex with and is supported by a woman

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "gigolo":
   Casanova, Don Juan, Lothario, Romeo, amoroso, bawd, beau,
   boyfriend, caballero, cavalier, cavaliere servente, esquire,
   fancy man, fellow, flame, gallant, inamorato, lady-killer,
   love-maker, madam, man, maquereau, necker, old man, pander,
   panderer, petter, philanderer, pimp, procurer, procuress, seducer,
   sheik, squire, sugar daddy, swain, white slaver, young man