/ Dictionary / Index L leucine: Meaning and Definition of Find definitions for: leu•cine Pronunciation: (l'sēn, -sin), [key] — n. Biochem. a white, crystalline, water-soluble amino acid, CHNO, obtained by the decomposition of proteins and made synthetically: essential in the nutrition of humans and animals. Abbr.: Leu; Symbol: L Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: leucine (Thesaurus) leucemia leucite Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language