ETYM Latin arbiter; ar- (for ad) + the root of betere to go; hence properly, one who comes up to look on.
1. Someone chosen to judge and decide a disputed issue; SYN. arbitrator.
2. Someone with the power to settle matters at will; SYN. supreme authority.
3. Judge, especially one chosen by disputing parties. arbiter elegantiae, (Latin) “judge of taste”, especially G. Petronius, supervisor of Nero’s entertainments.