Merriam-Webster Logo
SINCE 1828
dictionary
thesaurus
view recents

Ammonoidea

plural noun
Save Word
Am·​mo·​noi·​dea | \ ˌaməˈnȯidēə \

Definition of Ammonoidea

: an order of extinct chiefly Mesozoic Tetrabranchia comprising cephalopods having an external chambered shell that is either straight or variously curved or coiled — see ammonite entry 1

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Other Words from Ammonoidea

ammonoidean \ ¦amə¦nȯidēən \ adjective or noun

First Known Use of Ammonoidea

1884, in the meaning defined above

History and Etymology for Ammonoidea

New Latin, irregular from Ammonites + -oidea

Keep scrolling for more

Learn More about Ammonoidea

Time Traveler for Ammonoidea

Time Traveler

The first known use of Ammonoidea was in 1884

See more words from the same year

Statistics for Ammonoidea

Cite this Entry

“Ammonoidea.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Ammonoidea. Accessed 26 Nov. 2020.

Comments on Ammonoidea

What made you want to look up Ammonoidea? Please tell us where you read or heard it (including the quote, if possible).

Show Comments  Hide Comments 

WORD OF THE DAY

victual

Listen to the pronunciation of victual

See Definitions and Examples »

Test Your Vocabulary

A Thanksgiving Word Quiz

  • a traditional thanksgiving dinner
  • November comes from a word for which of the following numbers?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play
Ask the Editors
Word Games