The Collaborative International Dictionary of English v.0.48:
hydroxyproline \hydroxyproline\ n. A crystalline amino acid (C5H9NO3), a hydroxylated proline, obtained by hydrolysis of gelatin or collagen. Chemically it is 4-hydroxy-L-proline. It is classified as nonessential for growth in rats. [WordNet 1.5 +PJC]WordNet (r) 3.0 (2006):
hydroxyproline n 1: a crystalline amino acid obtained from gelatin or collagen