plac·​o·​derm | \ ˈpla-kə-ˌdərm How to pronounce placoderm (audio) \

Definition of placoderm

: any of a class (Placodermi) of extinct chiefly Devonian fishes with an armor of bony plates and primitive jaw structures

Examples of placoderm in a Sentence

Recent Examples on the Web From one layer to the next one above, no more trilobites or nightmarish placoderms or dimetrodons—entire animal reigns and ecosystems have vanished. Manu Saadia, Ars Technica, "The Ends of the World is a page-turner about mass extinction," 4 Sep. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'placoderm.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of placoderm

circa 1859, in the meaning defined above

History and Etymology for placoderm

New Latin Placodermi, ultimately from Greek plak-, plax + derma skin — more at derm-

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Time Traveler for placoderm

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The first known use of placoderm was circa 1859

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Cite this Entry

“Placoderm.” Dictionary, Merriam-Webster, Accessed 6 Aug. 2020.

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