someone chosen to judge and decide a disputed issue
The critic was considered to be an arbiter of modern literature. The arbitrator's authority derived from the consent of the disputants. An umpire was appointed to settle the tax case.
source: WordNet 3.0
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.
source: Webster 1913
verb
be a referee or umpire in a sports competition
source: WordNet 3.0
To decide as umpire; to arbitrate; to settle, as a dispute.
