/ Dictionary / Index R retinoid: Meaning and Definition of Find definitions for: ret•i•noid Pronunciation: (ret'n-oid"), [key] — n. any of a group of substances related to vitamin A and functioning like vitamin A in the body. —adj. resembling the retina. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. retinoblastoma retinol Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language