: 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
Their descendants began to diversify into the ancestors of modern amphibians and amniotes–the group that includes birds, reptiles, and mammals.
—
Laura Baisas, Popular Science, 14 May 2025
One possibility is that intelligence in vertebrates—animals with backbones, including mammals and birds—evolved once.
—Yasemin Saplakoglu, Wired News, 11 May 2025
They’ve been detected in the guts and tissues of many marine animals such as mammals, seabirds, turtles, zooplankton, fish, and sharks.
—Melissa Cristina Márquez, Forbes.com, 1 May 2025
Scientists earlier showed that Ronan, a resident of the Long Marine Laboratory at the University of California, Santa Cruz, was the first nonhuman mammal who could be trained to keep a beat, including moving in time with music.
—Gennaro Tomma, New York Times, 1 May 2025
See All Example Sentences for mammal
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Laura Baisas, Popular Science, 14 May 2025
One possibility is that intelligence in vertebrates—animals with backbones, including mammals and birds—evolved once.
—Yasemin Saplakoglu, Wired News, 11 May 2025
They’ve been detected in the guts and tissues of many marine animals such as mammals, seabirds, turtles, zooplankton, fish, and sharks.
—Melissa Cristina Márquez, Forbes.com, 1 May 2025
Scientists earlier showed that Ronan, a resident of the Long Marine Laboratory at the University of California, Santa Cruz, was the first nonhuman mammal who could be trained to keep a beat, including moving in time with music.
—Gennaro Tomma, New York Times, 1 May 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 29 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share