Tympan \Tym"pan\, n. [F., fr. tympanum a kettledrum, a panel of a door. See Tympanum, and cf. Tymp.]

1. A drum. [Obs.]

2. (Arch.) A panel; a tympanum.

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.

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.

Source: Webster's Revised Unabridged Dictionary (1913)