canker
can·ker / ˈkangkər/ • n. 1. a necrotic, fungal disease of apple and other trees that results in damage to the bark. ∎ an open lesion in plant tissue caused by infection or injury. ∎ fungal rot in some fruits and vegetables, e.g., parsnips and tomatoes.2. Med. an ulcerous condition or disease, in particular: ∎ (also canker sore) a small ulcer of the mouth or lips. ∎ another term for thrush2 (sense 2). ∎ ulceration of the throat and other orifices of birds, typically caused by a protozoal infection. ∎ (also ear can·ker) inflammation of the ear of a dog, cat, or rabbit, typically caused by a mite infestation. ∎ fig. a malign and corrupting influence that is difficult to eradicate: [in sing.] racism remains a canker. • v. 1. [intr.] (of woody plant tissue) become infected with canker: [as n.] (cankering) we found some cankering of the wood. 2. [tr.] [usu. as adj.] (cankered) infect with a pervasive and corrupting bitterness: he hated her with a cankered, shameful abhorrence.DERIVATIVES: can·ker·ous / -kərəs/ adj.