The Collaborative International Dictionary of English v.0.48:

Hematin \Hem"a*tin\, n. [Gr. a"i^ma, a"i`matos, blood.]
   1. Hematoxylin.
      [1913 Webster]

   2. (Physiol. Chem.) A bluish black, amorphous substance
      containing iron and obtained from blood. It exists the red
      blood corpuscles united with globulin, and the form of
      hemoglobin or oxyhemoglobin gives to the blood its red
      color.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Haematoxylin \H[ae]m`a*tox"y*lin\ (-t[o^]ks"[i^]*l[i^]n), n.
   [See H[ae]matoxylon.] (Chem.)
   The coloring principle of logwood. It is obtained as a yellow
   crystalline substance, C16H14O6, with a sweetish taste.
   Formerly called also hematin.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hematin
    n 1: a complex red organic pigment containing iron and other
         atoms to which oxygen binds [syn: heme, haem,
         hematin, haemitin, protoheme]