To suffer decomposition due to biological action, especially by fungi or bacteria.
The apple left in the cupboard all that time had started to rot.
To decline in function or utility.
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.
to rot vegetable fiber
To spend a long period of time (in an unpleasant place).
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.