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

A number of other mammals have structures inside their noses called the the vomeronasal organ (VNO) and main olfactory epithelium (MOE) designed to detect pheromones. —Bruce Y. Lee, Forbes.com, 29 Mar. 2025

The marine mammal — an infrequent visitor to the shores of the Emerald Isle — was spotted in the Waterford Estuary on the morning of March 25, according to a news release from the Irish Whale and Dolphin Group (IWDG), a conservation non-profit. —Brendan Rascius, Miami Herald, 28 Mar. 2025

In 2015, the largest toxic algae bloom ever recorded caused massive die-offs from Santa Barbara to Alaska, killing thousands of marine mammals, including sea lions and fin whales. —Karen Kucher, San Diego Union-Tribune, 28 Mar. 2025

There are more kinds of insects than there are mammals, birds and plants combined. —Nicholas Green, The Conversation, 24 Mar. 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