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can·ker       (kāng'kər)  Pronunciation Key  n.   Ulceration of the mouth and lips. An inflammation or infection of the ear and auditory canal, especially in dogs and cats. A condition in horses similar to but more advanced than thrush. A localized diseased or necrotic area on a plant part, especially on a trunk, branch, or twig of a woody plant, usually caused by fungi or bacteria. Any of several diseases of plants characterized by the presence of such lesions. A source of spreading corruption or decay. v.   can·kered, can·ker·ing, can·kers v.   tr. To attack or infect with canker. To infect with corruption or decay. v.   intr. To become infected with or as if with canker. [Middle English, from Old English cancer and from Old French cancre, both from Latin cancer, crab, malignant disease; see kar- in Indo-European roots.]

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canker 

WordNet - Cite This Source - Share This

canker
noun
1.	a fungal disease of woody plants that causes localized damage to the bark
2.	an ulceration (especially of the lips or lining of the mouth)
3.	a pernicious and malign influence that is hard to get rid of; "racism is a pestilence at the heart of the nation"; "according to him, I was the canker in their midst" [syn: pestilence]
verb
1.	become infected with a canker
2.	infect with a canker

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Canker

Can"ker\ (k[a^][ng]"k[~e]r), 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.

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Canker

Can"ker\ (k[a^][ng]"k[~e]r), v. t. [imp. & p. p. Cankered (-k[~e]rd); p. pr. & vb. n. Cankering.]

1. To affect as a canker; to eat away; to corrode; to consume.

No lapse of moons can canker Love. --Tennyson.

2. To infect or pollute; to corrupt. --Addison.

A tithe purloined cankers the whole estate. --Herbert.

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Canker

Can"ker\, v. i. 1. To waste away, grow rusty, or be oxidized, as a mineral. [Obs.]

Silvering will sully and canker more than gliding. --Bacom.

2. To be or become diseased, or as if diseased, with canker; to grow corrupt; to become venomous.

Deceit and cankered malice. --Dryden.

As with age his body uglier grows, So his mind cankers. --Shak.