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noun (1)

am·​mo·​nite ˈa-mə-ˌnīt How to pronounce ammonite (audio)
: any of a subclass (Ammonoidea) of extinct cephalopods especially abundant in the Mesozoic age that had flat spiral shells with the interior divided by septa into chambers
ammonitic adjective

Illustration of ammonite

Illustration of ammonite


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noun (2)

Am·​mon·​ite ˈa-mə-ˌnīt How to pronounce Ammonite (audio)
: a member of a Semitic people who in Old Testament times lived east of the Jordan between the Jabbok and the Arnon
Ammonite adjective

Examples of ammonite in a Sentence

Recent Examples on the Web
And her interest in fossils is linked from the start to her passionate attachment to another girl her own age who identifies an ammonite that the narrator finds on the beach. Ruth Franklin, The New Yorker, 2 Oct. 2023 For more than 2,000 years, Hinduism, Buddhism and the shamanic Himalayan religion of Bon have venerated Shaligrams – ancient fossils of ammonites, a class of extinct sea creatures related to modern squids. Holly Walters, The Conversation, 4 Aug. 2023 These included ichthyosaurs—dolphin-like reptiles—as well as turtles, fish, ammonites, crabs, mollusks, sharks, and at least one species of crocodyliform. Jeanne Timmons, Ars Technica, 23 Mar. 2023 Even the inexperienced are likely to find the 200-million-year-old shells of ammonites (extinct ancestors of mollusks) embedded in the rocks along the shore. Travel + Leisure Editors, Travel + Leisure, 10 Mar. 2023 Mary is tough and closed off, for example, like a shelled ammonite made hard as rock by external pressure. Josephine Livingstone, The New Republic, 27 Jan. 2021 The couple, who own a farm in nearby Hays, had previously collected ammonites and tiny bones while hiking through the shortgrass prairie. New York Times, 11 Feb. 2020 In addition, the amber contained the shells of squid-like critters called ammonites, which also lived in the sea. Matt Simon, Wired, 11 Mar. 2020 Giant mollusks with flanged shells that looked like alien cruisers disappeared forever, and many species of nautilus-like cephalopods called ammonites also went extinct. National Geographic, 18 Dec. 2019 See More

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

Word History


Noun (1)

New Latin ammonites, from Latin cornu Ammonis, literally, horn of Ammon

Noun (2)

Late Latin Ammonites, from Hebrew ʽAmmōn Ammon (son of Lot), descendant of Ammon

First Known Use

Noun (1)

1726, in the meaning defined above

Noun (2)

1530, in the meaning defined above

Time Traveler
The first known use of ammonite was in 1530

Dictionary Entries Near ammonite

Cite this Entry

“Ammonite.” Dictionary, Merriam-Webster, Accessed 29 Nov. 2023.

Kids Definition


am·​mo·​nite ˈam-ə-ˌnīt How to pronounce ammonite (audio)
: any of numerous flat spiral fossil shells of mollusks related to the nautilus that are especially abundant in the Mesozoic era of geological history
ammonitic adjective

More from Merriam-Webster on ammonite

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