The Collaborative International Dictionary of English v.0.48:

Player \Play"er\, n.
   1. One who plays, or amuses himself; one without serious
      aims; an idler; a trifler. --Shak.
      [1913 Webster]

   2. One who plays any game.
      [1913 Webster]

   3. A dramatic actor. --Shak.
      [1913 Webster]

   4. One who plays on an instrument of music. "A cunning player
      on a harp." --1 Sam. xvi. 16.
      [1913 Webster]

   5. A gamester; a gambler.
      [1913 Webster]

WordNet (r) 3.0 (2006):

player
    n 1: a person who participates in or is skilled at some game
         [syn: player, participant]
    2: someone who plays a musical instrument (as a profession)
       [syn: musician, instrumentalist, player]
    3: a theatrical performer [syn: actor, histrion, player,
       thespian, role player]
    4: a person who pursues a number of different social and sexual
       partners simultaneously
    5: an important participant (as in a business deal); "he was a
       major player in setting up the corporation"

Moby Thesaurus II by Grady Ward, 1.0:

152 Moby Thesaurus words for "player":
   Roscius, actor, actress, adventurer, amateur athlete, antagonist,
   archer, artist, artiste, athlete, bad guy, ballplayer, barnstormer,
   baseballer, baseman, batter, battery, betting ring, bettor,
   blocking back, boneshaker, bowman, cardshark, cardsharp,
   cardsharper, carouser, catcher, center, character, character actor,
   character man, character woman, child actor, coach, competitor,
   compulsive gambler, concert artist, contender, contestant,
   corrival, crap shooter, cricketer, cutup, defensive lineman,
   diseur, diseuse, dramatizer, emulator, end, entertainer, entrant,
   executant, feeder, foil, footballer, frisker, frolicker, funmaker,
   gambler, gamboler, games-player, gamester, guard, hazarder, heavy,
   histrio, histrion, impersonator, infielder, ingenue,
   instrumentalist, interpreter, jock, jumper, juvenile, lineman,
   maestro, matinee idol, merrymaker, mime, mimer, mimic, minstrel,
   minstrelsy, monologist, mummer, music maker, musician,
   offensive lineman, outfield, outfielder, pantomime, pantomimist,
   participant, performer, petty gambler, piker, playactor, playboy,
   pleasure-seeker, pleasurer, pleasurist, plunger, poloist,
   professional athlete, protean actor, pugilist, punter, quarterback,
   racer, reciter, reveler, rival, rollicker, sharp, sharper, sharpie,
   skater, skylarker, soloist, soubrette, speculator, sport,
   sporting man, sportsman, sportswoman, stage performer,
   stage player, stooge, straight man, stroller, strolling player,
   tackle, tailback, the field, theatrical, thespian, tinhorn,
   tipster, tout, toxophilite, trouper, tunester, utility man,
   venturer, vier, villain, virtuosa, virtuoso, wagerer, wingback,
   wrestler