Late Middle English; earliest use found in John Trevisa (c1342–?1402), translator. From classical Latin psīlōthrum a depilatory, white bryony (as the root was used as a depilatory; in post-classical Latin also as psilatrum) from Hellenistic Greek ψίλωθρον a depilatory, white bryony from ancient Greek ψιλοῦν to bare + -θρον, instrumental suffix.