Source : Webster's Revised Unabridged Dictionary (1913)

Archil \Ar"chil\ (?; 277), n. [OF. orchel, orcheil, It. orcella,
   oricello, or OSp. orchillo. Cf. {Orchil}.]
   1. A violet dye obtained from several species of lichen
      ({Roccella tinctoria}, etc.), which grow on maritime rocks
      in the Canary and Cape Verd Islands, etc. --Tomlinson.

   2. The plant from which the dye is obtained. [Written also
      {orchal} and {orchil}.]

Source : WordNet®

archil
     n 1: a purplish dye obtained from orchil lichens [syn: {orchil},
          {cudbear}]
     2: any of various lecanoras that yield the dye archil [syn: {orchil}]