/ Thesaurus / S Synonyms of supreme authority Find synonyms for: Noun1. arbiter, supreme authority, expertusage: someone with the power to settle matters at will; "she was the final arbiter on all matters of fashion"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: kiln Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language