a dog that swims well or is trained to retrieve waterfowl in hunting.
a person who feels at home in or on the water.
wa•ter•dogPronunciation: (wô'tur-dôg", -dog", wot'ur-), [key]
any of several large salamanders, as a mudpuppy or hellbender. Also,water dog.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.