- canker⇄canker, noun, verb.
- canker⇄noun 1. a spreading sore, especially a canker sore.
2. a fungous disease of plants, especially of fruit trees, that causes slow decay of the bark and tissues.
Ex. ... as killing as the canker to the rose (Milton).
3. (Figurative.) any - canker⇄v.t., v.i. to infect or be infected with canker; decay; rot.