The Collaborative International Dictionary of English v.0.48:

ballplayer \ballplayer\ n.
   1. an athlete who plays baseball.

   Syn: baseball player.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

ballplayer
    n 1: an athlete who plays baseball [syn: ballplayer, baseball
         player]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "ballplayer":
   amateur athlete, archer, athlete, baseballer, baseman, batter,
   battery, blocking back, bowman, catcher, center, coach, competitor,
   cricketer, defensive lineman, end, footballer, games-player,
   gamester, guard, infielder, jock, jumper, lineman,
   offensive lineman, outfield, outfielder, player, poloist,
   professional athlete, pugilist, quarterback, racer, skater, sport,
   sportsman, tackle, tailback, toxophilite, wingback, wrestler