Source : Webster's Revised Unabridged Dictionary (1913)

Orcin \Or"cin\, n. [Etymology uncertain: cf. F. orcine.] (Chem.)
   A colorless crystalline substance, {C6H3.CH3.(OH)2}, which is
   obtained from certain lichens ({Roccella}, {Lecanora}, etc.),
   also from extract of aloes, and artificially from certain
   derivatives of toluene. It changes readily into orcein.

Source : WordNet®

roccella
     n : a source of the dye archil and of litmus [syn: {Roccella
         tinctoria}]