Source : Webster's Revised Unabridged Dictionary (1913)

Placophora \Pla*coph"o*ra\, n. pl. [NL., from Gr. ?, ?, tablet +
   ? to bear.] (Zo["o]l.)
   A division of gastropod Mollusca, including the chitons. The
   back is covered by eight shelly plates. Called also
   {Polyplacophora}. See Illust. under {Chiton}, and
   {Isopleura}.

Polyplacophora \Pol`y*pla*coph"o*ra\, n. pl. [NL. See {Poly-},
   and {Placophora}.] (Zo["o]l.)
   See {Placophora}.

Source : WordNet®

Polyplacophora
     n : small class of marine mollusks comprising the chitons;
         sometimes considered an order of the subclass Amphineura
         [syn: {class Polyplacophora}]