ammonite

1 of 2

noun (1)

am·​mo·​nite ˈa-mə-ˌnīt 

: 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

ˌa-mə-ˈni-tik 

adjective

Illustration of ammonite

Ammonite

2 of 2

noun (2)

Am·​mon·​ite ˈa-mə-ˌnīt 

: 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

Noun

Visitors typically find ancient shark’s teeth and internal molds of ammonites and oyster shells. —Mark Price, Miami Herald, 5 Aug. 2025

The biggest of these whale-like creatures were apex predators, hunting ancient fish, ammonites, and even their smaller reptile relatives. —Lauren Leffer, Popular Science, 16 July 2025

The swirly shell that held the voice of the Little Mermaid in Disney’s 2023 live-action adaptation looked like the ancient marine mollusk called an ammonite. —Chantel Tattoli, New York Times, 20 May 2025

This colorful and iridescent ammonite is the only material classified as both a fossil and a gemstone. —Laura Baisas, Popular Science, 16 Apr. 2025

Word History

Etymology

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

Rhymes for ammonite

• acolyte
• aconite
• allanite
• alunite
• amberlite
• amorite
• amphitrite
• analyte
• anchorite
• andesite
• anhydrite
• ankerite

Kids Definition

ammonite

noun

am·​mo·​nite ˈam-ə-ˌnīt 

: 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

ˌam-ə-ˈnit-ik 

adjective