a brown, crystalline chloride of heme, CHNOFeCl, obtained when blood is treated with glacial acetic acid and sodium chloride: its production by this reaction is evidence of the presence of blood in fluids, stains, etc.
See hemin in American Heritage Dictionary 4
(hēˈmĭn)
noun
The reddish-brown crystalline chloride of heme, C34H32N4O4FeCl, produced when hemoglobin reacts with glacial acetic acid and sodium chloride in a laboratory test for the presence of blood.