/ Thesaurus / O Synonyms of outer boundary Find synonyms for: Noun1. periphery, fringe, outer boundary, boundary, edge, boundusage: the outside boundary or surface of somethingWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: profiterole Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language