/ Thesaurus / U Synonyms of unimaginable Find synonyms for: Adjective1. impossible, inconceivable, out of the question, unimaginable, unthinkable (vs. thinkable)usage: totally unlikelyWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language