Definition of placoid in English:

placoid

Syllabification: plac·oid
Pronunciation: /ˈplakoid
 
/

adjective

Zoology
(Of fish scales) toothlike, being made of dentin with a pointed backward projection of enamel, as in sharks and rays. Compare with ctenoid and ganoid.
More example sentences
  • Similar attempts had been underway in the dermal skeleton, stemming from Williamson's use of placoid scales from extant sharks as conceptual units in comparative analysis.
  • The earliest attempts to unravel the nature of development and patterning of the vertebrate dermoskeleton and visceral skeleton place central importance upon the nature of the placoid scales in living sharks.
  • Like other sharks, catsharks are covered with placoid scales.

Origin

mid 19th century: from Greek plax, plak- 'flat plate' + -oid.

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