The Collaborative International Dictionary of English v.0.48:

Punka \Pun"ka\, n. [Hind. pankh[=a] fan.]
   A machine for fanning a room, usually a movable fanlike frame
   covered with canvas, and suspended from the ceiling. It is
   kept in motion by pulling a cord. [Hindostan] [Written also
   punkah.] --Malcom.
   [1913 Webster]

WordNet (r) 3.0 (2006):

punkah
    n 1: a large fan consisting of a frame covered with canvas that
         is suspended from the ceiling; used in India for
         circulating air in a room