/ Thesaurus / I Synonyms of impugnable Find synonyms for: Adjective1. impugnable, questionable (vs. unquestionable)usage: subject to being discreditedWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: penury Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language