Can″ker (kăṉ″kẽr), n. [OE. canker, cancre, AS. cancer (akin to D. kanker, OHG chanchar.), fr. L. cancer a cancer; or if a native word, cf. Gr. � excrescence on tree, � gangrene. Cf. also OF. cancre, F. chancere, fr. L. cancer. See cancer, and cf. Chancre.]
1. A corroding or sloughing ulcer; esp. a spreading gangrenous ulcer or collection of ulcers in or about the mouth; — called also water canker, canker of the mouth, and noma.
2. Anything which corrodes, corrupts, or destroy.
The cankers of envy and faction.
Temple.
3. (Hort.) A disease incident to trees, causing the bark to rot and fall off.
4. (Far.) An obstinate and often incurable disease of a horse's foot, characterized by separation of the horny portion and the development of fungoid growths; — usually resulting from neglected thrush.
5. A kind of wild, worthless rose; the dog-rose.
To put down Richard, that sweet lovely rose.
And plant this thorm, this canker, Bolingbroke.
Shak.
Black canker. See under Black.