orchil

noun

1. a violet coloring matter obtained from certain lichens, chiefly species of Roccella.
2. any lichen yielding this dye.

noun

1. any of various lichens, esp any of the genera Roccella, Dendrographa, and Lecanora
2. Also called: cudbear a purplish dye obtained by treating these lichens with aqueous ammonia: contains orcinol, orcein, and litmus