The Collaborative International Dictionary of English v.0.48:

flyswat \fly"swat\, flyswatter \fly"swat*ter\n.
   An implement with a flat part (a mesh of metal or plastic)
   and a long handle, used to kill insects by striking them. The
   handle is typically about one foot long and the flat mesh at
   the end (usually of plastic) is about 5 inces square.

   Syn: swatter.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

flyswatter
    n 1: an implement with a flat part (of mesh or plastic) and a
         long handle; used to kill insects [syn: swatter,
         flyswatter, flyswat]