/ Dictionary / Index D decidua: Meaning and Definition of Find definitions for: de•cid•u•a Pronunciation: (di-sij'-u), [key] — pl. -cid•u•as, -cid•u•ae the endometrium of a pregnant uterus that in many of the higher mammals is cast off at parturition. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: decidua (Thesaurus) deciding deciduate Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language