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

Wild mammals can also become infected, especially those that scavenge on birds such as foxes. —Rick Sobey, Boston Herald, 9 Jan. 2026

By Christmas, the enormous mammal had done serious damage — turning on a gas line under the house —that forced Johnson to live without hot water. —Hannah Fry, Los Angeles Times, 9 Jan. 2026

With sea lions still eating thousands of salmon each spring at sites such as the Bonneville Dam, near Portland, some local fishers, tribal members, and politicians are pushing for the mammals’ body count to rise. —Katherine J. Wu, The Atlantic, 7 Jan. 2026

Areas of South Florida where the snakes have become dominant have seen a 90% to 99% decrease in sightings of mammal such as rabbits, opossums and raccoons. —Bill Kearney, Sun Sentinel, 7 Jan. 2026

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