arbiter arbiter /ˈɑːrbɪtɝ/

noun

1. Someone chosen to judge and decide a disputed issue  ( arbiter , arbitrator , umpire )
   someone chosen to judge and decide a disputed issue
    The critic was considered to be an arbiter of modern literature
   the critic was considered to be an arbiter of modern literature
    The arbitrator's authority derived from the consent of the disputants
   the arbitrator's authority derived from the consent of the disputants
    An umpire was appointed to settle the tax case
   an umpire was appointed to settle the tax case
   
2. Someone with the power to settle matters at will  ( arbiter , supreme authority )
   someone with the power to settle matters at will
    She was the final arbiter on all matters of fashion
   she was the final arbiter on all matters of fashion