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

Fifty of these small mammals were released on July 30, according to the trusts, and videos from other releases in the region captured their speedy acclimation back to their natural environment. —Irene Wright, Miami Herald, 4 Sep. 2025

As the region’s megadrought continues, roaming mammals, like black bears and mountain lions, may start to occupy larger ranges, widening their territory in the search for water and other resources. —John Leos, AZCentral.com, 3 Sep. 2025

Although the disease itself is rare in dogs, the discovery may soon expand experts’ understanding of the life-threatening heart disease that’s far more common in other mammals—including pet owners. —Andrew Paul, Popular Science, 3 Sep. 2025

Officials estimate that pythons have killed 95% of small mammals, as well as thousands of birds, in Florida's Everglades National Park. —Charlotte Phillipp, People.com, 1 Sep. 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