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

The site's paleontological importance is underscored by the presence of fossils found in the sedimentary layers, including ammonites, marine reptiles and microorganisms, all of which provide critical insight into life before and after the extinction event. — Jonathan Granoff, Newsweek, 29 Jan. 2025

Word History

Etymology

Noun (1)

borrowed from New Latin ammōnīta or ammōnītēs, from Latin Ammōn, the Egyptian god Ammon (in cornu Ammōnis, a name for the fossils, literally "horn of Ammon," alluding to the ram's head of the god and the hornlike shape of the stones) + -īta, -ītēs -ite entry 1

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