The Collaborative International Dictionary of English v.0.48:

Tympan \Tym"pan\, n. [F., fr. L. tympanum a kettledrum, a panel
   of a door. See Tympanum, and cf. Tymp.]
   1. A drum. [Obs.]
      [1913 Webster]

   2. (Arch.) A panel; a tympanum.
      [1913 Webster]

   3. (Print.) A frame covered with parchment or cloth, on which
      the blank sheets are put, in order to be laid on the form
      to be impressed.
      [1913 Webster]

   Tympan sheet (Print.), a sheet of paper of the same size as
      that to be printed, pasted on the tympan, and serving as a
      guide in laying the sheets evenly for printing. --W.
      Savage.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tympan
    n 1: a musical percussion instrument; usually consists of a
         hollow cylinder with a membrane stretched across each end
         [syn: drum, membranophone, tympan]