The Collaborative International Dictionary of English v.0.48:

Polystyle \Pol"y*style\, a. [Gr. ? with many columns; poly`s
   many + ? column: cf. F. polystyle.] (Arch.)
   Having many columns; -- said of a building, especially of an
   interior part or court; as, a polystyle hall. -- n. A
   polystyle hall or edifice.
   [1913 Webster]