I. ˈpȯr-pəs noun
Etymology: Middle English porpoys, from Anglo-French porpeis, from Medieval Latin porcopiscis, from Latin porcus pig + piscis fish — more at farrow , fish
Date: 14th century
1. : any of a family (Phocoenidae) of small gregarious toothed whales ; especially : a blunt-snouted usually largely black whale ( Phocoena phocoena ) of the North Atlantic and North Pacific that is five to eight feet (1.5 to 2.4 meters) long
2. : dolphin 1a(1)
II. intransitive verb
Date: 1909
1. : to leap or plunge like a porpoise
penguins… porpoise out of the water — David Lewis
2. : to rise and fall repeatedly