"an animal of the class Mammalia; an animal that suckles its young," 1826, Englished form of Modern Latin Mammalia (1773), coined 1758 by Linnaeus for that class of animals from neuter plural of Late Latin mammalis "of the breast," from Latin mamma "breast," which is cognate with mamma. With the exception of a few egg-laying species, all bear live young and have the mammary gland for the young to suck. All also are warm-blooded and breathe air. In Middle English, mammille was "a woman's breast" (early 15c.).

"weasel-like; pertaining to weasels," 1650s, from Latin mustelinus "of or belonging to weasels," from mustela; see mustelid + -ine (1).

marsupial mammal of Australia, 1798, from aboriginal Australian womback, wombar.

"of or pertaining to the mammals," 1813, from mammal + -ian. As a noun, "an animal of the class Mammalia," from 1835.

Central American mammal, 1796, from French (1670s), from an Algonquian word for the wolverine; the North American word was erroneously transferred by Buffon to the tropical animal.

carnivorous mammal, 1610s, alteration of wolvering (1570s), of uncertain origin, possibly from wolv-, inflectional stem of wolf (n.); or perhaps from wolver "one who behaves like a wolf" (1590s).

type of large, extinct, herbivorous mammal related to the sloth, 1799, a Latin compound from Greek elements; see mega- "great" + ther- "wild beast."

large, aquatic herbivorous mammal of the Indian Ocean and western Pacific, 1800 (by 1789 in French), from Malay (Austronesian) duyung, which is dugung in the Philippines.

"a carnivorous mammal of the Canidae family" (dogs, wolves, foxes, jackals), 1879, from Modern Latin Canidae, from Latin canis "dog" (from PIE root *kwon- "dog") + -idae.

nocturnal, omnivorous American marsupial mammal, c. 1600, from Powhatan (Algonquian) opassum, "equivalent to a proto-Algonquian term meaning 'white dog'" [Bright]. The colloquial form is possum (q.v.).