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

In a first for marine mammals, veterinarians have used bacteria-killing viruses to treat a beluga whale (Delphinapterus leucas) with a drug-resistant infection. — Margherita Bassi, Popular Science, 24 Sep. 2026

Like much of Lo’s music, the new project, named after a female mammal in heat, is centered around the age-old tension between the body and mind. — Cerys Davies, Los Angeles Times, 21 Sep. 2026

The domestication of transposons for new purposes has also been implicated in the evolution of the placenta — a defining feature of nearly all mammals. — Jake Buehler, Quanta Magazine, 21 Sep. 2026

Inside lay what conservationists call the most endangered mammal in America. — Shi En Kim, AZCentral.com, 21 Sep. 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