ˈprōˌlēn, -_lə̇n noun
( -s )
Etymology: German prolin, from p yr rol id in pyrrolidine
: a heterocyclic amino acid C 4 H 8 NCOOH that is a constituent of many proteins (as gliadin, casein, zein) and is obtained therefrom by hydrolysis; 2-pyrrolidine-carboxylic acid