: 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
Between backward-facing-feet, nipple-less milk secretion and egg-laying, platypuses and echidnas are some of the strangest mammals on Earth.
—
Margherita Bassi, Smithsonian Magazine, 1 May 2025
Based on the bones found in the cave, many of which show marks from cutting and scraping, the local menu included some birds and small mammals, but also bigger game like bison, deer, relatives of modern horses, and wild sheep and goats.
—ArsTechnica, 1 May 2025
Scientists identify key areas to protect Wildlife biologists since the 1930s have observed how birds and mammals use wooded fencerows, hedgerows, streamsides and other natural corridors to travel through agricultural regions in the U.S. and Canada.
—Reed Frederick Noss, The Conversation, 29 Apr. 2025
While polar bears are considered a marine mammal and spend most of their life on drifting sea ice, Visit Svalbard advises visitors to be prepared to encounter a polar bear anywhere in Svalbard.
—Saman Shafiq, USA Today, 29 Apr. 2025
See All Example Sentences for mammal
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Margherita Bassi, Smithsonian Magazine, 1 May 2025
Based on the bones found in the cave, many of which show marks from cutting and scraping, the local menu included some birds and small mammals, but also bigger game like bison, deer, relatives of modern horses, and wild sheep and goats.
—ArsTechnica, 1 May 2025
Scientists identify key areas to protect Wildlife biologists since the 1930s have observed how birds and mammals use wooded fencerows, hedgerows, streamsides and other natural corridors to travel through agricultural regions in the U.S. and Canada.
—Reed Frederick Noss, The Conversation, 29 Apr. 2025
While polar bears are considered a marine mammal and spend most of their life on drifting sea ice, Visit Svalbard advises visitors to be prepared to encounter a polar bear anywhere in Svalbard.
—Saman Shafiq, USA Today, 29 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 13 May. 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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