ˈhēm noun
also hem ˈhem ; or haem ˈhēm, ˈhem
( -s )
Etymology: International Scientific Vocabulary, from hematin
1. : a deep red iron-containing pigment C 34 H 32 N 4 O 4 Fe that is obtained from hemoglobin by treatment with acid to remove the globin, that is a ferrous derivative of protoporphyrin, and that readily oxidizes to hematin or hemin — called also ferroprotoporphyrin, protoheme, reduced hematin
2. : any of several compounds that are derived from protoporphyrin and iron in either the ferrous or ferric state and that constitute the nonprotein groups of some hemoproteins — compare hematin 2c, hemin 2