The Collaborative International Dictionary of English v.0.48:

Multiplane \Mul"ti*plane\, a.
   Having several or many planes or plane surfaces; as, a
   multiplane kite.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Multiplane \Mul"ti*plane\, n. [Multi- + plane.] (Aeronautics)
   An airplane with three or more superposed main wings, such as
   a triplane.
   [Webster 1913 Suppl.]