Meaning

noun a fungal disease of woody plants that causes localized damage to the bark

noun an ulceration (especially of the lips or lining of the mouth)

noun a pernicious and malign influence that is hard to get rid of

originFrom Middle English canker, cancre, from Old English cancer (“cancer; crab”), akin to Dutch kanker, Old High German chanchar. Ultimately from Latin cancer (“a cancer”). Doublet of cancer, a later borrowing from Latin, and chancre, which came through French.

Etymology from Wiktionary, CC BY-SA 3.0