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

For Lyme disease, deer feed the adult ticks that carry the bacterium but do not transmit it themselves; the spirochete is maintained by small mammals and birds, especially white-footed mice. — John Drake, Forbes.com, 4 July 2026

The researchers found that early mammals had relatively large, simple teeth with little variation in shape. — Ashley Vega, PEOPLE, 3 July 2026

In June, the bellowing and blubbery 5-year-old mammal hauled himself onto land for his twice-yearly tour of beachside towns in southern Tasmania state after months of feeding at sea. — ABC News, 3 July 2026

In the years since, a plethora of local, state and federal governmental actions have elevated the protection of marine mammals in the cove. — U T Readers, San Diego Union-Tribune, 2 July 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