noun
Etymology: Middle English waterdogge, from water + dogge dog — more at dog
1. : a dog (as a retriever or water spaniel) experienced and strong as a swimmer or trained to retrieve waterfowl
2.
a. dialect : otter
b. : any of several large salamanders: as
(1) : mud puppy ; especially : hellbender
(2) : giant newt
3. : a person (as a skilled sailor or swimmer) who is quite at ease on or in the water
4. : a small cloud that is held to indicate the approach of rain