/ Dictionary / Index R retinal: Meaning and Definition of Find definitions for: ret•i•nal Pronunciation: (ret'n-ul), [key] — adj. of or pertaining to the retina of the eye. ret•i•nal Pronunciation: (ret'n-al", -ôl"), [key] — n. Biochem. an orange pigment, CHO, that is the active component of rhodopsin and is liberated upon the absorption of light in the vision cycle; vitamin A aldehyde. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: retinal (Thesaurus) retinaculum retinite Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language