Plac"oid (?), a. [Gr. , , a tablet + -oid.] Zool.
Platelike; having irregular, platelike, bony scales, often bearing spines; pertaining to the placoids.
© Webster 1913.
Plac"oid, n. Zool. (a)
Any fish having placoid scales, as the sharks.
(b)
One of the Placoides.
© Webster 1913.