noun
or ae·tio·porphyrin |ē]d.ē(ˌ)ō also |e]+
Etymology: etio-, aetio- + porphyrin
: any of four isomeric porphyrins C 20 H 6 N 4 (CH 3 ) 4 (C 2 H 5 ) 4 ; especially : a violet crystalline pigment occurring in nature (as in petroleum and coal) and formed by degradation of chlorophyll and of heme