: 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 achievement marks a new milestone in the fight against the giant snakes, which are considered one of the greatest threats to the Everglades ecosystem because of their ability to prey on mammals, birds and other native wildlife.
—
Sonia Osorio, Miami Herald, 11 June 2026
The film explores the increasingly challenging coexistence of humans with polar bears – the world’s largest land predators – as climate change forces the mammals closer to human settlements to hunt for food, making dangerous encounters unavoidable.
—Annika Pham, Variety, 11 June 2026
After the non-avian dinosaur extinction 66 million years ago, placental mammals diversified explosively.
—Scott Travers, Forbes.com, 11 June 2026
In areas of Everglades National Park, where the snakes started showing up in the 1980s, sightings of mammals such as marsh rabbits, raccoons, opossums, bobcats and deer have plummeted by 80% to 99%, depending on species.
—Bill Kearney, Sun Sentinel, 11 June 2026
See All Example Sentences for mammal
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Sonia Osorio, Miami Herald, 11 June 2026
The film explores the increasingly challenging coexistence of humans with polar bears – the world’s largest land predators – as climate change forces the mammals closer to human settlements to hunt for food, making dangerous encounters unavoidable.
—Annika Pham, Variety, 11 June 2026
After the non-avian dinosaur extinction 66 million years ago, placental mammals diversified explosively.
—Scott Travers, Forbes.com, 11 June 2026
In areas of Everglades National Park, where the snakes started showing up in the 1980s, sightings of mammals such as marsh rabbits, raccoons, opossums, bobcats and deer have plummeted by 80% to 99%, depending on species.
—Bill Kearney, Sun Sentinel, 11 June 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 16 Jun. 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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