/ Dictionary / Index M methionine: Meaning and Definition of Find definitions for: me•thi•o•nine Pronunciation: (me-thī'u-nēn", -nin), [key] — n. Biochem. an amino acid, CHSCHCHCH(NH)COOH, found in casein, wool, and other proteins or prepared synthetically: used as a supplement to a special diet in the prevention and treatment of certain liver diseases. Abbr.: Met; Symbol: M Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: methionine (Thesaurus) methiocarb methocarbamol Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language