placoid
Americanadjective
adjective
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platelike or flattened
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(of the scales of sharks and other elasmobranchs) toothlike; composed of dentine with an enamel tip and basal pulp cavity
Etymology
Origin of placoid
1835–45; < Greek plak- (stem of pláx ) something flat, tablet + -oid
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Researchers in this study also revisited an analysis of fossilized placoid scales, or tiny tooth-like scales that cover sharks, from the megalodon.
From Salon ● Mar. 10, 2025
Shark teeth likely evolved from the jagged scales that cover their skin, called placoid scales.
From Textbooks ● Jan. 1, 2015
Placoid, plak′oid, adj. plate-like.—Placoid fishes, an order of fishes having placoid scales, irregular plates of hard bone, not imbricated, but placed near together in the skin.
From Chambers's Twentieth Century Dictionary (part 3 of 4: N-R) by Various
A singular species, rare, but easily recognized by its peculiar, placoid scales, large and firmly embedded in the peridial wall.
From The North American Slime-Moulds A Descriptive List of All Species of Myxomycetes Hitherto Reported from the Continent of North America, with Notes on Some Extra-Limital Species by Thomas H. (Thomas Huston) MacBride
The remains of fish are as yet confined to the upper part of the Silurian series; but some of these belong to placoid fish, which occupy a high grade in the scale of organization.
From Principles of Geology or, The Modern Changes of the Earth and its Inhabitants Considered as Illustrative of Geology by Sir Charles Lyell
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
