- 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 ’urjalla, of Mozarabic origin, ultimately from Latin &omacron;ricilla, 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.