Try Our Apps


Avoid these words. Seriously.


[plak-uh-durm] /ˈplæk əˌdɜrm/
any of various extinct jawed fishes of the class Placodermi, dominant in seas and rivers during the Devonian Period and characterized by bony armored plates on the head and upper trunk.
Origin of placoderm
1855-60; < New Latin Placodermi name of the class, plural of placodermus, equivalent to placo- (< Greek; see placoid, -o-) + -dermus -derm Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
Cite This Source
Examples from the Web for placoderm
Historical Examples
British Dictionary definitions for placoderm


any extinct bony-plated fishlike vertebrate of the class Placodermi, of Silurian to Permian times: thought to have been the earliest vertebrates with jaws
Word Origin
C19: from Greek plac-, plax a flat plate + -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
Cite This Source
placoderm in Science
Any of various extinct fishes of the class Placodermi of the Silurian and Devonian Periods, characterized by bony plates of armor covering the head and flanks. The bodies of placoderms were spindle-shaped or flattened, and their skeletons were usually partially bony and included a cranium. Placoderms were the first group of fish to evolve jaws, but are not closely related to the jawed fish of today.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source

Word of the Day

Nearby words for placoderm

Word Value for placoderm

Scrabble Words With Friends