|heməd.ō, |hēm-+ noun
Etymology: International Scientific Vocabulary hemat- + porphyrin
: any of several isomeric porphyrins C 20 H 6 N 4 (CH 3 ) 4 (CHOHCH 3 ) 2 (CH 2 CH 2 COOH) 2 that are hydrated derivatives of protoporphyrins ; especially : the deep red crystalline pigment obtained by treating hematin or heme with acid