1. 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. A third person, who is to decide a controversy or question submitted to arbitrators in case of their disagreement.

v. t.

  1. To decide as umpire; to arbitrate; to settle, as a dispute.
  2. To perform the duties of umpire in or for; as, to umpire a game.

v. i.

  1. To act as umpire or arbitrator.