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

Swimmer's itch is a skin rash caused by an allergic reaction to microscopic parasites that infect some birds and mammals, according to the Centers for Disease Control and Prevention. —Jalen Williams, Freep.com, 8 Aug. 2025

Whereas most mammals have roughly the same number of lifetime heartbeats, 1.5 billion, humans have about 2.5 billion. —Tad Friend, New Yorker, 4 Aug. 2025

The marine mammals — which can grow up to 8 feet and weigh up to 330 pounds — are typically found along the rocky coast of New Zealand. —Brendan Rascius, Miami Herald, 4 Aug. 2025

Don’t miss the chance to learn about one of Africa’s most elusive mammals at the Pangolin Conservation and Research Centre, which Noka proudly supports. —Chris Liebenberg, Travel + Leisure, 3 Aug. 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