- any of various dogs characteristically fond of the water; esp., any of several hunting dogs, as the American water spaniel, trained to retrieve waterfowl
- mud puppy
water dogwater dog
- A dog that takes easily to the water, especially one trained for hunting waterfowl.
- Informal A person who feels at home in or on the water.
- often wa·ter·dog a. See mudpuppy.b. A larval tiger salamander.