/ Dictionary / Index R retardant: Meaning and Definition of Find definitions for: re•tard•ant Pronunciation: (ri-tär'dnt), [key] — n. Chem. any substance capable of reducing the speed of a given reaction. —adj. retarding or tending to retard (usually used in combination): fire-retardant construction materials. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: retardant (Thesaurus) retard retardate Related Content Daily Word Quiz: abominable Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language