1813, from Modern Latin genus name Mastodon (1806), coined by French naturalist Georges Léopole Chrétien Frédéric Dagobert, Baron Cuvier (1769-1832) from Greek mastos "breast" (see masto-) + -odon "tooth" (see tooth); so called from the nipple-like projections on the crowns of the extinct mammal's fossil molars. Related: Mastodontic.
Any of several extinct mammals of the genus Mastodon (or Mammut). Mastodons resembled elephants and mammoths except that their molar teeth had conelike cusps rather than parallel ridges for grinding. Like elephants, mastodons had a pair of long, curved tusks growing from their upper jaw, but males also sometimes had a second pair from the lower jaw. Like mammoths, mastodons were covered with hair. They lived from the Oligocene Epoch to the end of the Ice Age.