The Collaborative International Dictionary
rhubarbarin
Chrysophanic \Chrys`o*phan"ic\, a. Pertaining to, or derived from, or resembling, chrysophane.
Chrysophanic acid (Chem.), a yellow crystalline substance extracted from rhubarb, yellow dock, sienna, chrysarobin, etc., and shown to be a derivative of an anthracene. It is used in the treatment of skin diseases; -- called also rhein, rheic acid, rhubarbarin, etc.
Wiktionary
rhubarbarin
n. chrysophanic acid