WordNet (r) 3.0 (2006):

emcee
    n 1: a person who acts as host at formal occasions (makes an
         introductory speech and introduces other speakers) [syn:
         master of ceremonies, emcee, host]
    v 1: act as a master of ceremonies [syn: emcee, compere]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "emcee":
   AFTRA, Abbot of Unreason, DJ, Lord of Misrule, MC, anchor man,
   announcer, attorney, auteur, bailiff, ballyhoo man, barker,
   broadcaster, butler, callboy, commentator, costume designer,
   costumer, costumier, croupier, curator, custodian, director,
   disk jockey, equestrian director, exhibitor, factor, guardian,
   housekeeper, impresario, landreeve, librarian, majordomo,
   makeup man, marshal, master of ceremonies, news commentator,
   newscaster, playreader, proctor, procurator, producer,
   program director, programmer, prompter, radiobroadcaster,
   ringmaster, scenewright, seneschal, set designer, showman,
   social director, sound-effects man, spieler, sportscaster,
   stage director, stage manager, steward, theater man, theatrician,
   ticket collector, toastmaster, usher, usherer, usherette