mammal

noun

mam·​mal ˈma-məl How to pronounce mammal (audio)
: 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
mammalian
mə-ˈmā-lē-ən How to pronounce mammal (audio)
ma-
adjective or noun
mammal-like
ˈma-məl-ˌlīk How to pronounce mammal (audio)
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
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.
But those early devices were clunky and expensive, good for large mammals such as moose and caribou, but not fit for commercial use on pets. — Tereza Pultarova, Space.com, 11 July 2026 What to do nearby Guests can snorkel at Molokini Crater, learn about marine mammals at the nearby Hawaiian Islands Humpback Whale National Marine Sanctuary, then get their food truck fix amidst lush tropical plants at South Maui Gardens. — Condé Nast, Condé Nast Traveler, 10 July 2026 In nearly every mammal that exhibits a nursing-specific reflex like this, the behavior fades out once that need disappears. — Scott Travers, Forbes.com, 10 July 2026 Enticknap said those areas enable the large sea mammals room to feed and regrow their populations. — Susanne Rust, Los Angeles Times, 9 July 2026 See All Example Sentences for mammal

Word History

Etymology

from base of New Latin Mammalia (Linnaeus), class name, noun derivative from neuter plural of mammālis, from Latin mamma "breast, udder" + -ālis -al entry 1 — more at mamma entry 1

First Known Use

1811, in the meaning defined above

Time Traveler
The first known use of mammal was in 1811

Rhymes for mammal

See All Rhymes for mammal

Browse Nearby Words

mamma's boy
mammal
mammalian
See all Nearby Words

Cite this Entry

“Mammal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mammal. Accessed 15 Jul. 2026.

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Kids Definition

mammal

noun
mam·​mal ˈmam-əl How to pronounce mammal (audio)
: 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

mammal

noun
mam·​mal ˈmam-əl How to pronounce mammal (audio)
: any of the higher vertebrate animals comprising the class Mammalia
mammalian
mə-ˈmā-lē-ən, ma- How to pronounce mammal (audio)
adjective or noun

More from Merriam-Webster on mammal

Nglish: Translation of mammal for Spanish Speakers

Britannica.com: Encyclopedia article about mammal

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