/ Thesaurus / F Synonyms of fallaciousness Find synonyms for: Noun1. fallaciousness, invalidity, invalidnessusage: result of a fallacy or error in reasoningWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language