\Roc*cel"lic\, a. [F. roccellique, fr. roccelle
archil, It. & NL. roccella, fr. It. rocca a rock, because
archil grows on rock.] (Chem.)
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}.