'Tympan sheet' definitions:

Definition of 'Tympan sheet'

From: GCIDE

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]