: 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
Domoic acid is the toxin responsible for killing hundreds of marine mammals.
—
Julia Jacobo, ABC News, 24 Apr. 2025
Authorities in America estimate that felines are responsible for killing between 1.4 and 3.7 billion birds and 6.9 to 20.7 billion mammals every year.
—Ross Rosenfeld, MSNBC Newsweek, 23 Apr. 2025
The scientists, led by fossil track specialist Conner Bennett, used advanced 3D imaging techniques to identify and analyze four sets of vertebrate trace fossils, including impressions left behind by prehistoric birds, mammals, lizards and invertebrates.
—Jonathan Limehouse, USA Today, 20 Apr. 2025
The virus is still circulating in U.S. dairy herds, poultry, wild birds and wild mammals.
—Susanne Rust, Los Angeles Times, 18 Apr. 2025
See All Example Sentences for mammal
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Julia Jacobo, ABC News, 24 Apr. 2025
Authorities in America estimate that felines are responsible for killing between 1.4 and 3.7 billion birds and 6.9 to 20.7 billion mammals every year.
—Ross Rosenfeld, MSNBC Newsweek, 23 Apr. 2025
The scientists, led by fossil track specialist Conner Bennett, used advanced 3D imaging techniques to identify and analyze four sets of vertebrate trace fossils, including impressions left behind by prehistoric birds, mammals, lizards and invertebrates.
—Jonathan Limehouse, USA Today, 20 Apr. 2025
The virus is still circulating in U.S. dairy herds, poultry, wild birds and wild mammals.
—Susanne Rust, Los Angeles Times, 18 Apr. 2025
See All Example Sentences for mammal
Cite this Entry
“Mammal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mammal. Accessed 28 Apr. 2025.
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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