: 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
See the seas’ fish, underwater mammals and birds, reptiles, coral and more!
—
Tracy Scott Forson, Smithsonian Magazine, 18 Apr. 2024
For context, that means the duck was flying as fast as Hall-of-Famer Aroldis Chapman’s fastball and twice as fast as the world’s fastest land mammal, the cheetah, can run.
—Katie Hill, Outdoor Life, 17 Apr. 2024
See all Example Sentences for mammal 
Tracy Scott Forson, Smithsonian Magazine, 18 Apr. 2024
For context, that means the duck was flying as fast as Hall-of-Famer Aroldis Chapman’s fastball and twice as fast as the world’s fastest land mammal, the cheetah, can run.
—Katie Hill, Outdoor Life, 17 Apr. 2024
See all Example Sentences for mammal
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'mammal.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Dictionary Entries Near mammal
Cite this Entry
“Mammal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mammal. Accessed 5 May. 2024.
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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