/ Thesaurus / A Synonyms of aphthous ulcer Find synonyms for: Noun1. aphthous ulcer, ulcer, ulcerationusage: a blister on the mucous membranes of the lips or mouth or gastrointestinal tractWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: loathe Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language