A gangrene or mortification which gradually spreads over the whole body (2 Timothy 2:17). In James 5:3 "cankered" means "rusted" (R.V.) or tarnished.

Noah Webster's New International Dictionary of the English Language

1. (n.) 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. (n.) Anything which corrodes, corrupts, or destroy.

3. (n.) A disease incident to trees, causing the bark to rot and fall off.

4. (n.) An obstinate and often incurable disease of a horse's foot, characterized by separation of the horny portion and the development of fungous growths; -- usually resulting from neglected thrush.

5. (n.) A kind of wild, worthless rose; the dog-rose.

6. (v. t.) To affect as a canker; to eat away; to corrode; to consume.

7. (v. t.) To infect or pollute; to corrupt.

8. (v. i.) To waste away, grow rusty, or be oxidized, as a mineral.

9. (v. i.) To be or become diseased, or as if diseased, with canker; to grow corrupt; to become venomous.