: 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
mammal-like
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
In a study recently published in the journal BioEssays, researchers at Imperial College London argue that increased exposure to burns influenced our DNA enough to separate us from all other mammals and primates.
—
Andrew Paul, Popular Science, 5 Feb. 2026
The carnivorous mammal's teeth-baring image suggests a wilderness pushed to the margins and lashing out.
—Felicia Feaster, AJC.com, 5 Feb. 2026
With fewer than 10,000 of the mammals remaining and both species slow breeders, conservationists say long-term restoration is crucial to prevent the Mexican long-nosed bat’s extinction.
—Susan Montoya Bryan, Los Angeles Times, 4 Feb. 2026
Texas, instead, turns to its own state small mammal — protected, particular and handled only by those who know how.
—Ana Gutierrez, Austin American Statesman, 3 Feb. 2026
See All Example Sentences for mammal
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Andrew Paul, Popular Science, 5 Feb. 2026
The carnivorous mammal's teeth-baring image suggests a wilderness pushed to the margins and lashing out.
—Felicia Feaster, AJC.com, 5 Feb. 2026
With fewer than 10,000 of the mammals remaining and both species slow breeders, conservationists say long-term restoration is crucial to prevent the Mexican long-nosed bat’s extinction.
—Susan Montoya Bryan, Los Angeles Times, 4 Feb. 2026
Texas, instead, turns to its own state small mammal — protected, particular and handled only by those who know how.
—Ana Gutierrez, Austin American Statesman, 3 Feb. 2026
See All Example Sentences for mammal
Cite this Entry
“Mammal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mammal. Accessed 15 Feb. 2026.
Copy CitationKids Definition
mammal
noun
mam·mal
ˈmam-əl 
: 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
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