mammal

noun

mam·​mal ˈma-məl 

: 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 

ma-

adjective or noun

mammal-like

ˈma-məl-ˌlīk 

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

Paleontologists have found fossilized remains of a giant possum-like mammal that lived 60 million years ago. —Julia Jacobo, ABC News, 24 June 2025

This small community of black-and-white mammals inhabits the Salish Sea, located in the inland Pacific Ocean waters between the state of Washington of British Columbia. —Sharon Udasin, The Hill, 23 June 2025

In recent years, however, more and more ivory has turned up from marine mammals (including whales, walruses, and seals), meaning that the discovery of the sperm whale tooth was a special one, providing new insights into the Valencina community’s connection to the sea. —Sam Walters, Discover Magazine, 19 June 2025

Such instances were reported in 257 cases in 2024, accounting for 26% of all mammals rescued from the Northern and Central Coast and admitted to the hospital. —Adrian Rodriguez, Mercury News, 16 June 2025

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

Rhymes for mammal

• camel
• hamel
• hamil
• trammel
• enamel
• glutamyl

Kids 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

mammal

noun

mam·​mal ˈmam-əl 

: any of the higher vertebrate animals comprising the class Mammalia

mammalian

mə-ˈmā-lē-ən, ma- 

adjective or noun