water rat (plural water rats)
- (US) Any of various rodents from Florida and southern Georgia, especially Neofiber alleni; the muskrat.
- 2004, James McConnachie, Rough Guide to the Loire, page 43,
- Otters are even harder to spot; the coypu, a North American water rat, is more commonly seen.
- (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.