1
: any of a family (Phocoenidae) of small gregarious toothed whales
especially
: a blunt-snouted usually dark gray whale (Phocoena phocoena) of the North Atlantic and North Pacific that typically ranges from 5 to 6 feet (1.5 to 1.8 meters) in length
2
: dolphin sense 1a(1)
—not used technically
Note: While not closely related, porpoises and dolphins share a physical resemblance that often leads to misidentification. Porpoises typically have flat, spade-shaped teeth, triangular dorsal fins, and shortened beaks with relatively small mouths while dolphins have cone-shaped teeth, curved dorsal fins, and elongated beaks with larger mouths.
porpoised; porpoising; porpoises
1
: to leap or plunge like a porpoise
… penguins call as they porpoise out of the water …—
David Lewis
David LewisWhen traveling in the water, Adélie penguins move by porpoising.—David G. Ainley
David G. Ainley2
: to rise and fall repeatedly
Examples of porpoise in a Sentence
Recent Examples on the Web
Juana Summers, NPR, 26 Dec. 2025
Since its discovery in 1987, cetacean morbillivirus has emerged as a lethal threat to marine life, causing devastating respiratory, neurological, and immune system failure in whales, dolphins, and porpoises.
—Mrigakshi Dixit, Interesting Engineering, 18 Dec. 2025
Hadley Hall Meares, Vanity Fair, 22 Dec. 2025
Other words, like robot, poodle and porpoise, are fun to discover, but also well-documented.
—Literary Hub, 20 Oct. 2025
See All Example Sentences for porpoise
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Noun
This virus can cause immunosuppression and severe disease in cetaceans–whales, dolphins and porpoises–and has caused several mass die-offs in these animals.
—Juana Summers, NPR, 26 Dec. 2025
Since its discovery in 1987, cetacean morbillivirus has emerged as a lethal threat to marine life, causing devastating respiratory, neurological, and immune system failure in whales, dolphins, and porpoises.
—Mrigakshi Dixit, Interesting Engineering, 18 Dec. 2025
Verb
Mincemeat pies, crane, swan, brawn (terrine made with a pig’s head and served with mustard), goose and lamprey pie, and even porpoise (served dressed with vinegar and breadcrumbs) were all popular holiday fare.
—Hadley Hall Meares, Vanity Fair, 22 Dec. 2025
Other words, like robot, poodle and porpoise, are fun to discover, but also well-documented.
—Literary Hub, 20 Oct. 2025
See All Example Sentences for porpoise
Cite this Entry
“Porpoise.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/porpoise. Accessed 4 Jan. 2026.
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