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

As of February, the Australian mainland and New Zealand didn’t have any cases of the H5N1 strain, which has spread among birds worldwide and affected some mammals. —Kathleen Magramo, CNN Money, 19 June 2026

This large cone size helps its seeds to survive fires, allowing small birds and mammals to then disperse them into new areas in the Mediterranean Scrub of Southern California. —Torben Rick, The Conversation, 18 June 2026

Suddenly, a driver is faced with the possibility of being crushed by a mammal the size of a grand piano—and its massive antlers. —Mack Degeurin, Popular Science, 18 June 2026

But screwworms sicken all kinds of warm-blooded mammals, including, less commonly, humans. —Kara Finnstrom, CBS News, 18 June 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