- water dog, water rat - a person who enjoys being in or on the water
--1 is a kind of sailor, crewman
- water vole, water rat, Arvicola amphibius - common large Eurasian vole
--2 is a kind of vole, field mouse
--2 is a member of Arvicola, genus Arvicola - water rat - any of various amphibious rats
--3 is a kind of rodent, gnawer, gnawing animal
--3 has particulars: beaver rat