canker

noun

1. (countable, uncountable)A plant disease marked by gradual decay.
2. (countable, uncountable)A region of dead plant tissue caused by such a disease.

   “Slightly sunken brown cankers of variable size and shape affect stem parts primarily below the soil line.”

3. (countable, uncountable)A worm or grub that destroys plant buds or leaves; cankerworm.

   “loathsome canker lives in sweetest bud[…]”

4. (countable, uncountable)A corroding or sloughing ulcer; especially a spreading gangrenous ulcer or collection of ulcers in or about the mouth.
5. (countable, uncountable)Anything which corrodes, corrupts, or destroys.

   “the canker of destitution and violence.”

   “the cankers of envy and faction”

   “There’s canker at the root, your seed Denies the blessing of the sun, The light essential to your need. Your hopes are murdered and undone.”

6. (countable, uncountable)A kind of wild rose; the dog rose.

   “To put down Richard, that ſweet louely Roſe, And plant this thorne, this canker Bullingbrooke?”

7. (countable, uncountable)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.
8. (countable, uncountable)An avian disease affecting doves, poultry, parrots and birds of prey, caused by Trichomonas gallinae.
9. (Cornwall, countable, rare, uncountable)A crab.

   “This Caſtoꝛ liueth by water and lande, he loueth to feede vpon Crabbes and Cankers of the Sea.”

   “It is this power of active motion which has obtained it a local name in the West of Cornwall, where, as crabs in general are termed "cankers," this species is distinguished by the name of "flying canker."”

verb

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

   “Still onward winds the dreary way; / I with it; for I long to prove / No lapse of moons can canker Love, / Whatever fickle tongues may say.”

2. (transitive)To infect or pollute; to corrupt.
3. (intransitive)To waste away, grow rusty, or be oxidized, as a mineral.
4. (intransitive)To be or become diseased, or as if diseased, with canker; to grow corrupt; to become venomous.

   “as with age his body uglier grows, So his mind cankers.”

   “[…] the road, always in bad condition, was edged with dog roses that scratched the paint. Blossom after blossom crept past them, draggled by the ungenial year: some had cankered, others would never unfold:”