/ Thesaurus / I Synonyms of irrationally Find synonyms for: Adverb1. irrationallyusage: in an irrational manner; "they acted irrationally"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language