umpire

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Sports A person appointed to rule on plays, especially in baseball.
2. n. A person appointed to settle a dispute that mediators have been unable to resolve; an arbitrator. See Synonyms at judge.
3. v. To act as referee for; rule or judge.
4. v. To be or act as a referee or an arbitrator.

Century Dictionary and Cyclopedia

1. n. A person to whose sole decision a controversy or question between parties is referred; one agreed upon as a judge, arbiter, or referee in case of conflict of opinions; specifically, a person selected to see that the rules of a game, as cricket or base-ball, are enforced, and to decide disputed or debatable points.
2. n. In law, a third person called in to decide a controversy or question submitted to arbitrators when the arbitrators do not agree in opinion. Synonyms Arbitrator, Referee, etc. See judge.
3. To decide as umpire; settle, as a dispute. Specifically To enforce the rules of (a game), and decide disputed points: as, to umpire a game of baseball.
4. To act as umpire.

Wiktionary

1. n. tennis The official who presides over a tennis game sat on a high chair.
2. n. cricket One of the two white-coated officials who preside over a cricket match.
3. n. baseball One of usually 4 officials who preside over a baseball game.
4. n. American football The official who stands behind the line on the defensive side.
5. n. Australian rules football A match official on the ground deciding and enforcing the rules during play. As of 2007 the Australian Football League uses 3, or in the past 2 or just 1. The other officials, the goal umpires and boundary umpires, are normally not called just umpires alone.
6. n. law A person who arbitrates between contending parties
7. v. sports To act as an umpire in a game.

GNU Webster's 1913

1. n. A person to whose sole decision a controversy or question between parties is referred; especially, one chosen to see that the rules of a game, as cricket, baseball, or the like, are strictly observed.
2. n. (Law) A third person, who is to decide a controversy or question submitted to arbitrators in case of their disagreement.
3. v. To decide as umpire; to arbitrate; to settle, as a dispute.
4. v. colloq. To perform the duties of umpire in or for.
5. v. To act as umpire or arbitrator.

WordNet 3.0

1. v. be a referee or umpire in a sports competition
2. n. an official at a baseball game
3. n. someone chosen to judge and decide a disputed issue