an essential amino acid, CHSCHCHCH(NH)COOH, that contains sulfur, obtained from various proteins and used as a food supplement and in medicine
Origin:
me(thyl) + thion(ic) + -ine
See methionine in American Heritage Dictionary 4
noun
A sulfur-containing essential amino acid, C5H11NO2S, obtained from various proteins or prepared synthetically and used as a dietary supplement and in pharmaceuticals.