cetacean
noun
ce·ta·cean
si-ˈtā-shən 
: any of an order (Cetacea) of aquatic mostly marine mammals that includes the whales, dolphins, porpoises, and related forms and that have a torpedo-shaped nearly hairless body, paddle-shaped forelimbs but no hind limbs, one or two nares opening externally at the top of the head, and a horizontally flattened tail used for locomotion
cetacean
adjective
Examples of cetacean in a Sentence
Recent Examples on the Web
The ancient Greeks recognized that cetaceans breathe air, give birth to live young, produce milk, and have hair—all features of mammals.
—
Encyclopedia Britannica, 2 Apr. 2026
In general, birth observations for wild cetaceans — the group that includes whales, dolphins and porpoises — are exceedingly rare, representing only 10% of species, Gruber noted via email.
—Mindy Weisberger, CNN Money, 30 Mar. 2026
Begun in 1970, this is the longest-running research project on a population of wild cetaceans – whales, dolphins and porpoises – in the world.
—Laela Sayigh, The Conversation, 23 Mar. 2026
The pair spent their childhood summers camping here, collecting whale bones and learning from their father about regional folklore, including tales from the nearby whaling station at Bahía del Águila, which processed 4,000 cetaceans between 1906 and 1920.
—Mark Johanson, Outside, 14 Mar. 2026
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Encyclopedia Britannica, 2 Apr. 2026
In general, birth observations for wild cetaceans — the group that includes whales, dolphins and porpoises — are exceedingly rare, representing only 10% of species, Gruber noted via email.
—Mindy Weisberger, CNN Money, 30 Mar. 2026
Begun in 1970, this is the longest-running research project on a population of wild cetaceans – whales, dolphins and porpoises – in the world.
—Laela Sayigh, The Conversation, 23 Mar. 2026
The pair spent their childhood summers camping here, collecting whale bones and learning from their father about regional folklore, including tales from the nearby whaling station at Bahía del Águila, which processed 4,000 cetaceans between 1906 and 1920.
—Mark Johanson, Outside, 14 Mar. 2026
See All Example Sentences for cetacean
Cite this Entry
“Cetacean.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cetacean. Accessed 5 Apr. 2026.
Copy CitationKids Definition
cetacean
noun
ce·ta·cean
si-ˈtā-shən
: any of an order of aquatic mammals (as a whale, dolphin, or porpoise)
cetacean
adjective
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