fielder

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An athlete who plays a position on the field in a sport, especially an outfielder in baseball.

from The Century Dictionary.

• noun In base-ball, cricket, etc., one whose duty is to catch or stop balls; specifically, in base-ball, any one of the players in the field, and especially one of the three players who stand behind and at the right and left respectively of second base. See base-ball.
• noun A dog trained to the pursuit of game in the field.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Ball Playing) A ball payer who stands out in the field to catch or stop balls.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun cricket A player of the fielding side, whose task is to gather the ball after the batsman has hit it, to catch the batsman out, or to prevent him from scoring.
• noun baseball, softball A defensive player in the field.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a member of the cricket team that is fielding rather than batting
• noun a member of the baseball team that is in the field instead of at bat