Source : Webster's Revised Unabridged Dictionary (1913)

Bat's-wing \Bat's"-wing"\or Batwing \Bat"wing\, a.
   Shaped like a bat's wing; as, a bat's-wing burner.

Source : WordNet®

batwing
     adj : formed or shaped like a bat's wing; "a dress with batwing
           sleeves"
     n : one of a pair of swinging doors (as at the entrance to a
         western saloon)