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

Despite their mass, the mammals do know how to accelerate in water and on land. — Dennis Romero, NBC news, 8 Aug. 2026

Blumstein said this is the second longest study of individual identifiable mammals in the world. — Maddie Rhodes, USA Today, 8 Aug. 2026

SeaWorld San Antonio welcomed seven more beluga whales on Tuesday, the latest development in the international effort to relocate dozens of the mammals from a shuttered Canadian theme park. — Jared Ochacher, CBS News, 6 Aug. 2026

One main way that these milks aren’t similar—and one important reason why other animal milks should be pasteurized to ensure safety—is simply how the different milks are delivered from mammals to humans. — Parents, 6 Aug. 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