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 2022, scientists detected the strain in mammals. —Joe Spring, Smithsonian Magazine, 20 Dec. 2024

And because the fossil record shows the widespread decline of American megafauna starting around the same time — with North America losing 70% of its large mammals, and South America losing more than 80% — many researchers surmised that humans’ arrival led to mass extinctions. —Christina Larson, Los Angeles Times, 20 Dec. 2024

And because the fossil record shows the widespread decline of American megafauna starting around the same time - with North America losing 70% of its large mammals, and South America losing more than 80% - many researchers surmised that humans' arrival led to mass extinctions. —CBS News, 20 Dec. 2024

But flu viruses can also mutate quickly, and since 2022, H5N1 has been infecting a growing variety of mammals, including dairy cattle. —Brenda Goodman, CNN, 19 Dec. 2024

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

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