placoid

[ plak-oid ]

/ ˈplæk ɔɪd /

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adjective

platelike, as the scales or dermal investments of sharks.

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Origin of placoid

1835–45; <Greek plak- (stem of pláx) something flat, tablet + -oid

Words nearby placoid

plack, plackart, placket, placode, placoderm, placoid, plafond, plagal, plagal cadence, plage, plagiarism

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use placoid in a sentence

The tail is asymmetrical (heterocercal), and numerous placoid scales (dermal denticles) are embedded in the skin.
The New Gresham Encyclopedia|Various
They pass by quite insensible gradations into normal placoid scales, such as cover the general surface of the body.
The Vertebrate Skeleton|Sidney H. Reynolds
In some cases the placoid scales are enlarged to form plates or spines capped or coated with enamel.
The Vertebrate Skeleton|Sidney H. Reynolds
The Thornback Skate is covered with prickles (placoid scales).
Stories of the Universe: Animal Life|B. Lindsay

The teeth of Selachii are fundamentally identical with placoid scales.
The Vertebrate Skeleton|Sidney H. Reynolds

British Dictionary definitions for placoid

placoid

/ (ˈplækɔɪd) /

adjective

platelike or flattened

(of the scales of sharks and other elasmobranchs) toothlike; composed of dentine with an enamel tip and basal pulp cavity

Word Origin for placoid

C19: from Greek plac-, plax flat

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