noun
arbiter
AR-bih-ter/ˈɑːrbɪtər/
A person whose judgment establishes a decision or standard.
Both sides accept the retired judge as arbiter of their dispute.

Etymology
The pieces suggest someone who goes to a place as a witness or judge. Latin used the word for eyewitnesses and, in law, someone who hears and decides a case—the role retained in English.
In context
as a public servant if his net worth grows drastically while in office our laws presume unexplained weal is ill gotten our Chief Justice of the Supreme Court the primary Arbiter and interpreter of our laws declared
More examples
- The magazine became an arbiter of fashion.
- An independent arbiter reviewed the competing claims.
- The competition needs arbiters whose judgment everyone trusts.
Forms
arbiter · arbiters
Similar words
- arbitrator
- Usually formally appointed to settle a particular dispute.
- judge
- May exercise official legal authority or evaluate a competition.