The Collaborative International Dictionary of English v.0.48:

Harmine \Har"mine\ (h[aum]r"m[i^]n or -m[=e]n), n.[See
   Harmaline.] (Chem.)
   An alkaloid accompanying harmaline (in the Peganum
   harmala), and obtained from it by oxidation. It is a white
   crystalline substance.
   [1913 Webster]