The Collaborative International Dictionary of English v.0.48:

battledoor \bat"tle*door`\, n. [OE. batyldour. A corrupted form
   of uncertain origin; cf. Sp. batallador a great combatant, he
   who has fought many battles, Pg. batalhador, Pr. batalhador,
   warrior, soldier, fr. L. battalia; or cf. Pr. batedor batlet,
   fr. batre to beat, fr. L. batuere. See Battle, n.]
   1. An instrument, with a handle and a flat part covered with
      parchment or crossed with catgut, used to strike a
      shuttlecock in play; also, the play of battledoor and
      shuttlecock. [Also spelled battledore.]
      [1913 Webster]

   2. [OE. battleder.] A child's hornbook. [Obs.] --Halliwell.
      [1913 Webster]