arbiter

/ˈär-bə-tər/

Middle English arbitour, arbitre, borrowed from Anglo-French, borrowed from Latin arbiter "eyewitness, onlooker, person appointed to settle a dispute," perhaps, if going back to *ad-biteros, from ad- ad-*-biteros, derivative from a base *-bit- akin to bītere, baetere, bētere "to go," of obscure origin

noun

  1. a person with power to decide a dispute : judge

  2. a person or agency whose judgment or opinion is considered authoritative

The mayor will act as the final arbiter in any dispute between board members.

noun

  1. a person who prescribes, rules on, or is a recognized authority on matters of social behavior and taste