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

Bison, America's national mammal and the largest mammal in Colorado, once lived nearly statewide, Colorado Parks and Wildlife says. —Christa Swanson, CBS News, 22 Mar. 2026

Concentrations of beryllium, copper, chromium, nickel and lead in particular were significantly above established safety thresholds for marine life, prompting fears for the long-term health of fish, marine mammals and the marine food chain. —Los Angeles Times, 20 Mar. 2026

Unlike iguanas, which feed on plants and vegetation, these lizards have a broad diet and eat insects, fish, amphibians, reptiles, birds, and their eggs and small mammals, according to the FWC. —Julia Gomez, USA Today, 20 Mar. 2026

Echidnas are also egg-laying mammals, but their melanosomes appear to follow the solid pattern seen across roughly 120 other mammal species examined in the research. —Ryan Brennan, Miami Herald, 20 Mar. 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