Main Entry: plac·o·derm

Pronunciation: \ˈpla-kə-ˌdərm\

Function: noun

Etymology: New Latin Placodermi, ultimately from GK plak-, plax + derma skin — more at derm-

Date: circa 1865

: any of a class (Placodermi) of extinct chiefly Devonian fishes with an armor of bony plates and primitive jaw structures