Meaning

noun ulcerated chilblain on the heel

originOrigin unknown, but first attested in Middle English. suggested origins and context Attestations in Shakespeare's time seem to suggest it was intended as mildly vulgar (compare zit) and metaphorical; see more at this Open Literature article, which claims Welsh as most probable origin: * Compare Welsh cibi, cibwst (“chilblain(s)”), although this itself may borrow from Middle English, and we may be…

Etymology from Wiktionary, CC BY-SA 3.0