mammal

noun

mam·​mal ˈma-məl How to pronounce mammal (audio)
: 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
mammalian
mə-ˈmā-lē-ən How to pronounce mammal (audio)
ma-
adjective or noun
mammal-like
ˈma-məl-ˌlīk How to pronounce mammal (audio)
adjective
or less commonly mammallike
mammal-like behavior
mammallike reptiles

Examples of mammal in a Sentence

Human beings, dogs, and cats are all mammals.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Other marine mammals, such as harbor seals, have also been known to swim into the Delta. — Anne Ewbank, Sacbee.com, 15 Oct. 2026 People with alpha-gal syndrome may experience allergic reactions after consuming mammalian meat or other products derived from mammals, including certain dairy products. — Stephen Underwood, Hartford Courant, 14 Oct. 2026 De-extincting a placental mammal like a dire wolf is a comparatively straightforward process. — Jeffrey Kluger, Time, 14 Oct. 2026 When the midges transfer the virus to mammals, the fever isn’t necessarily obvious, but other symptoms can be. — Kris Millgate, Outdoor Life, 14 Oct. 2026 See All Example Sentences for mammal

Word History

Etymology

from base of New Latin Mammalia (Linnaeus), class name, noun derivative from neuter plural of mammālis, from Latin mamma "breast, udder" + -ālis -al entry 1 — more at mamma entry 1

First Known Use

1811, in the meaning defined above

Time Traveler
The first known use of mammal was in 1811

Rhymes for mammal

See All Rhymes for mammal

Browse Nearby Words

mamma's boy
mammal
mammalian
See all Nearby Words

Cite this Entry

“Mammal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mammal. Accessed 22 Oct. 2026.

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Kids Definition

mammal

noun
mam·​mal ˈmam-əl How to pronounce mammal (audio)
: any of a class of warm-blooded vertebrates that include human beings and all other animals that nourish their young with milk produced by mammary glands and have the skin usually more or less covered with hair

Medical Definition

mammal

noun
mam·​mal ˈmam-əl How to pronounce mammal (audio)
: any of the higher vertebrate animals comprising the class Mammalia
mammalian
mə-ˈmā-lē-ən, ma- How to pronounce mammal (audio)
adjective or noun

More from Merriam-Webster on mammal

Britannica.com: Encyclopedia article about mammal

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