ce·​ta·​cean | \si-ˈtā-shən \

Definition of cetacean 

: 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

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Other Words from cetacean

cetacean adjective
cetaceous \-​shəs \ adjective

Examples of cetacean in a Sentence

Recent Examples on the Web

Similar results have been found in other families of mammals, like ungulates (deer, camels, and the like) and cetaceans (whales and dolphins). Cathleen O'grady, Ars Technica, "The evolutionary mystery of gigantic human brains," 23 Aug. 2018 Indeed, there is evidence that many cetaceans—that is, whales, dolphins and porpoises—have strong and complicated family and social ties. Alison Gopnik, WSJ, "Like Us, Whales May Be Smart Because They’re Social," 16 Aug. 2018 Among marine mammals, pinnipeds, such as seals, do—but cetaceans, such as whales and dolphins, do not. Anna Diamond, Smithsonian, "Do Marine Mammals Yawn and More Questions From Our Readers," 28 June 2018 The North Atlantic right whale, for example, reaches over 50 feet in length and is one of the most endangered cetaceans on the planet. Brian Switek, Smithsonian, "Today’s Whales Are Huge, But Why Aren’t They Huger?," 27 June 2018 One of the article’s authors, vertebrate biologist Nel Beaumont, wrote in an email that there were not enough older books about cetaceans in their sample to determine whether accuracy had improved over time. Claire Eamer, Smithsonian, "How Children’s Books Reveal Our Evolving Relationship With Whales," 27 Mar. 2018 As Ruth Schuster at Haaretz reports, bones of both cetaceans were found near Gibraltar, indicating that the whales ranged much further afield, even using the Mediterranean Sea as a calving ground. Jason Daley, Smithsonian, "Romans May Have Hunted Whales to Extinction in Their Home Waters," 11 July 2018 Not just an ordinary cetacean but a blue whale, the biggest of the species. Tom Titus, latimes.com, "On Theater: Friends come in all shapes and sizes," 24 May 2018 The plan is to survey sites where offshore wind farms might be built, to assess the risk of any development there interfering with local cetaceans. The Economist, "A better way to transmit messages underwater," 10 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cetacean.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of cetacean

1835, in the meaning defined above

History and Etymology for cetacean

ultimately from Latin cetus whale, from Greek kētos

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cetane number


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Last Updated

18 Nov 2018

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Time Traveler for cetacean

The first known use of cetacean was in 1835

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English Language Learners Definition of cetacean

: a mammal (such as a whale, dolphin, or porpoise) that lives in the ocean

More from Merriam-Webster on cetacean

Britannica.com: Encyclopedia article about cetacean

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