lysine lysin • lysine intolerance · · · Info · Definitions · Characters · · lysine · · Text Latin · · Script 6 · · Length 2 · · Syllables Definitions · · · (noun) an essential amino acid found in proteins; occurs especially in gelatin and casein. · · Noun Definition 1 Characters · · e latin small letter e U+0065 i latin small letter i U+0069 l latin small letter l U+006C n latin small letter n U+006E s latin small letter s U+0073 y latin small letter y U+0079