ˈthrēəˌnēn, -_nə̇n noun
( -s )
Etymology: probably from threon- (as in threonic acid ) + -ine
: a crystalline alpha-amino acid CH 3 CHOHCH(NH 2 )COOH known in six optically isomeric forms; 2-amino-3-hydroxy-butyric acid ; especially : the levorotatory l -form related to d -threose that is obtained by hydrolysis of various proteins (as casein and egg proteins) and is essential to normal nutrition