The Collaborative International Dictionary of English v.0.48:

Musician \Mu*si"cian\, n. [F. musicien.]
   One skilled in the art or science of music; esp., a skilled
   singer, or performer on a musical instrument.
   [1913 Webster]

WordNet (r) 3.0 (2006):

musician
    n 1: someone who plays a musical instrument (as a profession)
         [syn: musician, instrumentalist, player]
    2: artist who composes or conducts music as a profession

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "musician":
   artist, artiste, belly dancer, burlesque queen, chorine,
   chorus boy, chorus girl, conjurer, coryphee, dancer, dancing girl,
   ecdysiast, entertainer, exotic dancer, female impersonator, geisha,
   geisha girl, guisard, guiser, hoofer, impersonator, magician,
   mountebank, mummer, nautch girl, peeler, performer, player,
   prestidigitator, public entertainer, show girl, singer, stripper,
   stripteaser, stripteuse, vaudevillian, vaudevillist, virtuoso