placoid

[ plak-oid ]

adjective
  1. platelike, as the scales or dermal investments of sharks.

Origin of placoid

1
1835–45; <Greek plak- (stem of pláx) something flat, tablet + -oid

Words Nearby placoid

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How to use placoid in a sentence

  • The tail is asymmetrical (heterocercal), and numerous placoid scales (dermal denticles) are embedded in the skin.

  • 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).

  • The teeth of Selachii are fundamentally identical with placoid scales.

    The Vertebrate Skeleton | Sidney H. Reynolds

British Dictionary definitions for placoid

placoid

/ (ˈplækɔɪd) /


adjective
  1. platelike or flattened

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

Origin of placoid

1
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