tampion

from WordNet (r) 3.0 (2006)

tampion
    n 1: plug for the muzzle of a gun to keep out dust and moisture
         [syn: {tampion}, {tompion}]

from The Collaborative International Dictionary of English v.0.48

Tampion \Tam"pi*on\, n. [F. tampon, tapon, tape, of Dutch or
   German origin. See {Tap} a pipe or plug, and cf. {Tamp},
   {Tampop}, {Tompion}.] [Written also {tampeon}, and
   {tompion}.]
   1. A wooden stopper, or plug, as for a cannon or other piece
      of ordnance, when not in use.
      [1913 Webster]

   2. (Mus.) A plug for upper end of an organ pipe.
      [1913 Webster]