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

Named for the German ornithologist and zoologist Constantin Wilhelm Lambert Gloger, the rule applies primarily to birds and mammals. — Encyclopedia Britannica, 3 Sep. 2026

Protected by the Guarani for generations, towering trees rise here as toucans and other birds fly through the canopy and coatis — a mammal in the raccoon family — roam the forest floor. — Marina Dias, Washington Post, 2 Sep. 2026

The iconic musician and humanitarian inspired the name for Dolly the Sheep, the world’s first mammal cloned from an adult cell, in 1996. — Ashley Strickland, CNN Money, 29 Aug. 2026

The relocation effort gained urgency after Marineland warned officials that it could be forced to euthanize the mammals if the export permits were not quickly approved. — Thao Nguyen, USA Today, 28 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