To suffer decomposition due to biological action, especially by fungi or bacteria.
Example: "The apple left in the cupboard all that time had started to rot."
To decline in function or utility.
Example: "Your brain will rot if you spend so much time on the computer, tony!"
To (cause to) deteriorate in any way, as in morals; to corrupt.
To make putrid; to cause to be wholly or partially decomposed by natural processes.
Example: "To rot vegetable fiber"
To spend a long period of time (in an unpleasant place).
Example: "To rot in hell"
To expose, as flax, to a process of maceration, etc., for the purpose of separating the fiber; to ret.
To talk nonsense.
Destroyed or damaged by rot.
Deeply annoyed or irritated.