tym·pan 
(t
ĭm
p
ən)
n.1. Printing A padding, as of paper or cloth, placed over the platen of a press to regulate the pressure on the sheet being printed.
2. Architecture A tympanum.
3. A tightly stretched sheet or membrane, as on the head of a drum.
[Middle English timpan, drum, from Old English timpana, from Latin tympanum, from Greek tumpanon.]