- any of a number of lichens (genera Roccella, Dendrographa, and Lecanora) yielding purple dyes
- any of these, including litmus
- Any of several lichens, chiefly of the genus Roccella, from which a dye is obtained.
- The violet dyestuff obtained from any of these lichens.
Origin of orchilMiddle English orchell, ultimately from Old Catalan orxella, from Andalusian dialectal Arabic ’urjālla, of Mozarabic origin, ultimately from Latin ōricilla, a little ear (probably from the resemblance of the lichens to growths on the fetlocks of mules, somewhat resembling little ears ), diminutive of auris, ear; see auricle.