- any of various rodents that live on the banks of streams and ponds
- a. Any of various semiaquatic rodents, especially Neofiber alleni of Florida and southern Georgia, that resemble the muskrat but are smaller and have a round tail.b. See muskrat.
- Slang A petty thief or ruffian who frequents waterfronts.
(plural water rats)
- (US) Any of various rodents from Florida and southern Georgia, especially Neofiber alleni; the muskrat.
- (Australia) The rakali, Hydromys chrysogaster.
- (informal) The European water vole, Arvicola amphibius, formerly Arvicola terrestris.
- (US, slang) A petty thief or waterfront ruffian.
- (slang) A person fond of water sports.
- (slang, Australia) A member of the water police.