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