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

The smelly, hairy animals with terrible eyesight are actually a type of mammal known as a collared peccary. —Shelby Slade, AZCentral.com, 24 July 2025

Not only were scaly reptiles proliferating, but the predecessors of mammals were also evolving fur and whiskers. —Riley Black, Smithsonian Magazine, 23 July 2025

Wildlife scientists believe dust bathing may also be a way for some mammals to claim their territory by scent-marking when rolling in the dirt. —Ernie Cowan, San Diego Union-Tribune, 20 July 2025

Up until the late 1990s, the mammals were famously abundant in Everglades National Park. —Bill Kearney, Sun Sentinel, 17 July 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