: 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
The viral disease affects mammals’ central nervous systems and is primarily spread through scratches and bites from infected animals.
—
Nathan Diller, USA Today, 4 Dec. 2025
Many are small mammals (mice, raccoons, assorted rodents) while some are simply indeterminate cute little beings.
—Hazlitt, 3 Dec. 2025
Scientists at the Bavarian State Collections of Natural History (Staatliche Naturwissenschaftliche Sammlungen Bayerns, or SNSB) have looked into the mouths of bears through time and found something truly unusual for mammals.
—New Atlas, 2 Dec. 2025
Researchers estimate that the spill also killed between 600,000 and 800,000 seabirds, as many as 167,000 sea turtles and over a thousand marine mammals like dolphins and whales.
—Kylie Williams, Miami Herald, 29 Nov. 2025
See All Example Sentences for mammal
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Nathan Diller, USA Today, 4 Dec. 2025
Many are small mammals (mice, raccoons, assorted rodents) while some are simply indeterminate cute little beings.
—Hazlitt, 3 Dec. 2025
Scientists at the Bavarian State Collections of Natural History (Staatliche Naturwissenschaftliche Sammlungen Bayerns, or SNSB) have looked into the mouths of bears through time and found something truly unusual for mammals.
—New Atlas, 2 Dec. 2025
Researchers estimate that the spill also killed between 600,000 and 800,000 seabirds, as many as 167,000 sea turtles and over a thousand marine mammals like dolphins and whales.
—Kylie Williams, Miami Herald, 29 Nov. 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 7 Dec. 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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