The Collaborative International Dictionary of English v.0.48:

Multivalve \Mul"ti*valve\, Multivalvular \Mul`ti*val"vu*lar\, a.
   [Multi- + valve, valvular: cf. F. multivalve.]
   1. Having many valves.
      [1913 Webster]

   2. (Zool.) Many-valved; having more than two valves; -- said
      of certain shells, as the chitons.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Multivalve \Mul"ti*valve\, n. [Cf. F. multivalve.] (Zool.)
   Any mollusk which has a shell composed of more than two
   pieces.
   [1913 Webster] Multivalve