Definition of: porpoise

(pôr′pəs) noun plural ·poises or ·poise
1. A gregarious cetacean, of the genus Phocaena, without a distinct beak; especially, P. phocaena of the North Atlantic and Pacific, from 5 to 6 feet long, blackish above and white below.
2. Any small cetacean; popularly, the common dolphin or the bottlenose. [<OF porpeis, porpois, lit., hog fish <L porcus a hog + piscis a fish]
COMMON PORPOISE
(Smaller than the 7 to 8 foot common dolphin)