roccellic, a. [F. roccellique, fr. roccelle archil, It. & NL. roccella, fr. It. rocca a rock, because archil grows on rock.].
Pertaining to, or designating, a dibasic acid of the oxalic series found in archil (Roccella tinctoria, etc.), and other lichens, and extracted as a white crystalline substance C17H32O4. [1913 Webster]