/ Dictionary / Index T tyrosine: Meaning and Definition of Find definitions for: ty•ro•sine Pronunciation: (tī'ru-sēn", -sin, tir'u-), [key] — n. Biochem. a crystalline amino acid, HOCHCHCH(NH)COOH, abundant in ripe cheese, that acts as a precursor of norepinephrine and dopamine. Abbr.: Tyr; Symbol: Y Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: tyrosine (Thesaurus) tyrosinase tyrosinemia Related Content Daily Word Quiz: tranquil Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language