mas·​to·​don ˈma-stə-ˌdän How to pronounce mastodon (audio)
: any of various extinct mammals (genus Mammut synonym Mastodon) of the elephant family existing from the Miocene through the Pleistocene that are distinguished from the related mammoths chiefly by molar teeth with cone-shaped cusps
: one that is unusually large
mastodonic adjective
mastodont adjective or noun

Examples of mastodon in a Sentence

mom-and-pop stores just can't compete with these mastodons of retailing
Recent Examples on the Web In the next gallery are the familiar mastodon and Irish elk, as well as a display of human evolution. Ed Stannard, Hartford Courant, 11 Mar. 2024 Visitors who entered the building’s rotunda could walk along the evolution of the earth before man’s appearance — baked vegetation covered with lichen, then a cross section of a California redwood tree that was nearly 6 feet in diameter, followed by animal including a mastodon, mammoth and a whale. Andrew Johnston, Chicago Tribune, 30 May 2024 Due to the shape of their tusks, fights between mastodons (like the two Mammut pacificus depicted here) resulted in characteristic jaw injuries. Ron Amadeo, Ars Technica, 3 May 2023 Scientists are beginning to tell such ancient stories by looking at the layers of minerals that once accumulated each day on the outside of the tusks of mammoths and mastodons. Carl Zimmer, New York Times, 17 Jan. 2024 At the moment, however, whether mastodons experienced musth or whether their tusks preserve hormones is unknown. Ron Amadeo, Ars Technica, 3 May 2023 For example, experts have identified a suite of characteristics that set sauropods apart from the mastodons and giant rhinos of the Cenozoic. Riley Black, Popular Science, 9 Nov. 2023 Thomas Jefferson, who was nicknamed Mr. Mammoth for his interest in fossils, instructed Lewis and Clark to keep an eye out for mastodons on their journey to the Pacific. Rivka Galchen, The New Yorker, 6 Nov. 2023 Temperatures changed, severe droughts persisted, and food sources may have dwindled as animals like mammoths, mastodons, and giant sloths went extinct. Laura Baisas, Popular Science, 28 Sep. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'mastodon.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


borrowed from New Latin Mastodont-, Mastodon, genus name, Latinization of French mastodonte, vernacular name for the animal, from Greek mastós "breast, nipple" (probably from a pre-Greek substratal language) + French -odonte -odont; so named from the nipple-like cusps on the crowns of the molar teeth

First Known Use

1811, in the meaning defined at sense 1

Time Traveler
The first known use of mastodon was in 1811

Dictionary Entries Near mastodon

Cite this Entry

“Mastodon.” Dictionary, Merriam-Webster, Accessed 22 Jun. 2024.

Kids Definition


: any of various huge extinct mammals related to the mammoths and existing elephants

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