plural noun
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

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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

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The first known use of Ammonoidea was in 1884

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Cite this Entry

“Ammonoidea.” Dictionary, Merriam-Webster, Accessed 14 Apr. 2021.

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