[ os-truh-koh-durm ]
/ ˈɒs trə koʊˌdɜrm /
Save This Word!

any of several extinct jawless fishes of the Ordovician, Silurian, and Devonian periods, having the body enclosed in an armor of bony plates.
Were you ready for a quiz on this topic? Well, here it is! See how well you can differentiate between the uses of "was" vs. "were" in this quiz.
Question 1 of 7
“Was” is used for the indicative past tense of “to be,” and “were” is only used for the subjunctive past tense.

Origin of ostracoderm

1890–95; <New Latin Ostracodermi, plural ofOstracodermus<Greek ostrakódermos with a shell, equivalent to óstrako(n) shell, tile + -dermos-derm
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

British Dictionary definitions for ostracoderm

/ (ˈɒstrəkəˌdɜːm, ɒsˈtrækə-) /

any extinct Palaeozoic fishlike jawless vertebrate of the group Ostracodermi, characterized by a heavily armoured body

Word Origin for ostracoderm

C19: via New Latin from Greek ostrakon shell + -derm
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for ostracoderm

[ ŏstrə-kŏ-dûrm′ ]

Any of various extinct primitive jawless fishes of the Ordovician through the Devonian Period. Most ostracoderms had their heads or entire bodies encased in fused bony plates. Some or all ostracoderms are sometimes classified together with the modern cyclostomes (lampreys and hagfish).
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.