mam·​mal | \ˈma-məl \

Definition of mammal 

: any of a class (Mammalia) of warm-blooded higher vertebrates (such as placentals, marsupials, or monotremes) that nourish their young with milk secreted by mammary glands, have the skin usually more or less covered with hair, and include humans

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Other Words from mammal

mammalian \mə-​ˈmā-​lē-​ən, ma-​ \ adjective or noun

Examples of mammal in a Sentence

Human beings, dogs, and cats are all mammals.

Recent Examples on the Web

Nicholas Pyenson, the curator of fossil marine mammals at the Smithsonian National Museum of Natural History, has been tracking the long tail of whale evolution for decades, from deserts brimming with bones to the seas themselves. Brian Switek, Smithsonian, "Today’s Whales Are Huge, But Why Aren’t They Huger?," 27 June 2018 The result is a landscape of plains, wetlands and forest roamed by thousands of hoofed mammals. The Economist, "A Dutch park that mimics nature angers animal-rights activists," 7 June 2018 About 22,000 of the 40-ton mammals pass within 2 miles of the coast on their trip south from the Bering Sea. Maria Finn, San Francisco Chronicle, "Don’t miss these great places to see California wildlife, from insects to whales," 28 Mar. 2018 All aspects of the natural world are represented here, from a vast collection of taxidermy mammals, to depictions of the life of Native American tribes, to an entire hall dedicated to marine life—including a life-size model of a gigantic blue whale. John Wogan, Condé Nast Traveler, "25 Best Museums in New York City," 27 Feb. 2018 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 Scientists say the giant constrictor snakes, which can grow over 20 feet long, have eliminated 99 percent of the native mammals in the Everglades, decimating food sources for native predators such as panthers and alligators. Jennifer Kay,, "Hunters bag 1,000 pythons in Florida Everglades," 22 May 2018 Earlier this year in Greenbelt, Maryland, an amateur paleontologist found a fossil showing distinct proof of mammals and dinosaurs interacting. David Grossman, Popular Mechanics, "11-Year-Old Stumbles Across 475-Million-Year-Old Fossil," 4 May 2018 Aurek, beluga whale at Shedd Aquarium (with help from Timothy Ward, supervisor of marine mammals) Daily agenda: swim, dive, train, such as veterinarian simulations or enrichment practices. Grace Wong,, "What do a sommelier, a Bears lineman and a penguin eat for lunch?," 26 Apr. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'mammal.' 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 mammal

1813, in the meaning defined above

History and Etymology for mammal

New Latin Mammalia, from Late Latin, neuter plural of mammalis of the breast, from Latin mamma breast

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Statistics for mammal

Last Updated

8 Dec 2018

Look-up Popularity

Time Traveler for mammal

The first known use of mammal was in 1813

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English Language Learners Definition of mammal

: a type of animal that feeds milk to its young and that usually has hair or fur covering most of its skin


mam·​mal | \ˈma-məl \

Kids Definition of mammal

: a warm-blooded animal (as a dog, mouse, bear, whale, or human being) with a backbone that feeds its young with milk produced by the mother and has skin usually more or less covered with hair


mam·​mal | \ˈmam-əl \

Medical Definition of mammal 

: any of the higher vertebrate animals comprising the class Mammalia

Other Words from mammal

mammalian \mə-​ˈmā-​lē-​ən, ma-​ \ adjective or noun

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More from Merriam-Webster on mammal

Spanish Central: Translation of mammal

Nglish: Translation of mammal for Spanish Speakers

Britannica English: Translation of mammal for Arabic Speakers Encyclopedia article about mammal

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to enclose within walls

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