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• ammonite
  ammonite

  noun

  the coiled, chambered fossil shell of an ammonoid.
• Ammonite
  Ammonite

  noun

  an inhabitant of Ammon.

ammonite

¹ American  

[am-uh-nahyt] / ˈæm əˌnaɪt /

noun

1. the coiled, chambered fossil shell of an ammonoid.

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ammonite ² American  

[am-uh-nahyt] / ˈæm əˌnaɪt /

noun

1. a nitrogenous mixture consisting chiefly of dried animal fats, usually obtained from livestock carcasses, and used as a fertilizer.

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Ammonite ³ American  

[am-uh-nahyt] / ˈæm əˌnaɪt /

noun

1. an inhabitant of Ammon.

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adjective

1. of or relating to the Ammonites.

ammonite ¹ British  

/ ˌæməˈnɪtɪk, ˈæməˌnaɪt /

noun

1. any extinct marine cephalopod mollusc of the order Ammonoidea, which were common in Mesozoic times and generally had a coiled partitioned shell. Their closest modern relative is the pearly nautilus

2. the shell of any of these animals, commonly occurring as a fossil

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ammonite ² British  

/ ˈæməˌnaɪt /

noun

1. an explosive consisting mainly of ammonium nitrate with smaller amounts of other substances, such as TNT

2. a nitrogenous fertilizer made from animal wastes

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ammonite Scientific  

/ ăm′ə-nīt′ /

1. Any of the ammonoids belonging to the order Ammonitida and living during the Jurassic and the Cretaceous Periods. Ammonites had a thick, very ornamental chambered shell with highly defined, wavy sutures between the chambers.

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Other Word Forms

• Ammonitish
  adjective
• ammonitic
  adjective
• ammonitoid
  adjective
• pre-Ammonite
  adjective

Etymology

Origin of ammonite¹

1700–10; < New Latin Ammonites < Medieval Latin ( cornū ) Ammōn ( is ) (literally, horn of Ammon ) + -ītes -ite ¹; fossil so called from its resemblance to the horn of Jupiter Ammon

Origin of ammonite²

First recorded in 1600–10; ammo(nium) + nit(rat)e

Origin of Ammonite³

First recorded in 1605–15; Ammon + -ite ¹

Explanation

An ammonite is an extinct sea creature, a cephalopod distantly related to squids and octopuses. You can also use the word ammonite for the fossilized shells of these ancient animals. The last ammonites died out 66 million years ago, and some ammonite fossils are over 400 million years old. Although their closest living relations don't have hard shells, ammonites did. These ancient mollusks' shells were flat, coiled disks. Their name comes from the creatures' resemblance to a coiled ram's horn: Ammonite is derived from Ammon (or Amun), the name of an Egyptian god who was portrayed wearing ram's horns on his head.

Example Sentences

See Examples For:

ammonite Ammonite

"After, I said to Casey: 'Well, I just wanted to find a little ammonite."

From BBC ● Apr. 22, 2026

The name of this cuvée refers to the ammonite fossils in the ancient soils of the vineyards.

From Washington Post ● Dec. 15, 2022

Fossils such as this opalized ammonite can develop gradually when a mixture of water and silica permeates deeply buried shells, bones or teeth left behind after other remains rot away.

From Scientific American ● Sep. 5, 2022

If you’ve seen one ammonite, you may think you’ve seen them all.

From New York Times ● Dec. 10, 2021

I was walking along still staring into my ammonite when an elbow swung out of nowhere and knocked my head backward on its hinge.

From "Black Swan Green" by David Mitchell

Ammonite is the fourth Sednoid discovered to date.

From Space Scoop ● Jul. 31, 2025

A number of other high profile TV and film productions have used the Dorset Coast as locations in recent years including Wonka, Ammonite and Future TX.

From BBC ● Jun. 29, 2023

Recognition for Anning grew after the 2020 release of the film Ammonite, starring Kate Winslet.

From Science Magazine ● May 25, 2022

In Ammonite, this quiet, crushing film, writer-director Francis Lee introduces Mary Anning, a 19th-century palaeontologist whose important fossil finds were appropriated by the male scientific establishment.

From The Guardian ● Feb. 21, 2021

“Its Latin name. Ammonite family. You can tell by these close tight ribs it's got, with these extra-fat ones every so often...”

From "Black Swan Green" by David Mitchell