Rot  —v. (-tt-) 1 (of animal or vegetable matter) lose its original form by the chemical action of bacteria, fungi, etc.; decay. 2 gradually perish or waste away (left to rot in prison). 3 cause to rot, make rotten. —n. 1 rotting; decay. 2 slang nonsense (talks rot). 3 decline in standards etc. (rot set in). —int. Expressing incredulity or ridicule. [old english]