late Old English cancer "spreading ulcer, cancerous tumor," from Latin cancer "malignant tumor," literally "crab" (see cancer); influenced in Middle English by Old North French cancre "canker, sore, abscess" (Old French chancre, Modern French chancre). The word was the common one for "cancer" until c.1700. Also used since 15c. of caterpillars and insect larvae that eat plant buds and leaves. As a verb from late 14c. Related: Cankered; cankerous. Canker blossom is recorded from 1580s.
canker can·ker (kāng'kər)
Ulceration of the mouth and lips.
An acute inflammation or infection of the ear and auditory canal, especially in dogs and cats.
a gangrene or mortification which gradually spreads over the whole body (2 Tim. 2:17). In James 5:3 "cankered" means "rusted" (R.V.) or tarnished.