/ Thesaurus / M Synonyms of mental retardation Find synonyms for: Noun1. retardation, mental retardation, backwardness, slowness, subnormality, stupidityusage: lack of normal development of intellectual capacitiesWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: pallid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language