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

But genetic evidence kept grouping whales close to hippos and other mammals with hoofed toes, called artiodactyls. —Riley Black, Smithsonian Magazine, 9 Apr. 2025

In 2003, a group of European scientists tried to clone a recently extinct mammal called the bucardo, a mountain goat from the Pyrenees. —D. T. Max, New Yorker, 7 Apr. 2025

These large predators were lost during the Late Pleistocene extinctions that eliminated many large land mammals from the Americas near the end of the most recent glaciation. —John Timmer, ArsTechnica, 7 Apr. 2025

Unlike their smaller cousins, dire wolves hunted large ice age mammals, including mammoths and horses. —John W. Dean, MSNBC Newsweek, 7 Apr. 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