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

Plague is an infectious disease caused by the bacteria Yersinia pestis, usually found in small mammals and their fleas, WHO said. — Don Sweeney, Sacbee.com, 6 Oct. 2026

The World Health Organization describes pneumonic plague as a less common but severe form of plague — a disease caused by Yersinia pestis, a bacterium usually found in small mammals and their fleas. — ABC News, 5 Oct. 2026

The sugar, found in most mammals but not in humans, prompts the antibodies that trigger an allergic reaction. — Bob Drogin, Los Angeles Times, 4 Oct. 2026

To convey the brutality of the method, activists tend to bring up the counsel of the World Society for the Protection of Animals, which has advised that nitrogen hypoxia is not fit to put down any mammal. — Doreen St. Félix, New Yorker, 3 Oct. 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