The Collaborative International Dictionary of English v.0.48:

Xanthorhamnin \Xan`tho*rham"nin\, n. [Xantho- + NL. Rhamnus, the
   generic name of the plant bearing Persian berries.] (Chem.)
   A glucoside extracted from Persian berries as a yellow
   crystalline powder, used as a dyestuff.
   [1913 Webster]