/ Dictionary / Index O ornithine: Meaning and Definition of Find definitions for: or•ni•thine Pronunciation: (ôr'nu-thēn"), [key] — n. Biochem. an amino acid, HN(CH)CH(NH)COOH, obtained by the hydrolysis of arginine and occurring as an intermediate compound in the urea cycle of mammals. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: ornithine (Thesaurus) ornithic ornithischian Related Content Daily Word Quiz: blithesome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language