placoid

[ plak-oid ]

/ ˈplæk ɔɪd /

adjective

platelike, as the scales or dermal investments of sharks.

Nearby words

Origin of placoid

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

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for placoid

The Thornback Skate is covered with prickles (placoid scales).
Stories of the Universe: Animal Life|B. Lindsay
In some cases the placoid scales are enlarged to form plates or spines capped or coated with enamel.
The Vertebrate Skeleton|Sidney H. Reynolds
In the groups of fishes above the Selachians, the coating of placoid elements shows various modifications.
Encyclopaedia Britannica, 11th Edition, Volume 14, Slice 3|Various
In the Selachians the bony skeleton is restricted to the placoid elements.
Encyclopaedia Britannica, 11th Edition, Volume 14, Slice 3|Various

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