D defs.my
Entry 3 senses Webster, 1913

Tympan

· Tym·pan · IPA /ˈtɪmpən/
01 n. A drum.
  1. 1.
    A drum.[Obs.]
  2. 2.
    A panel; a tympanum.(Arch.)
  3. 3.
    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.(Print.)
Phrases & compounds
Tympan sheet — 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.