A tympanum (pl.: tympana; from Greek and Latin words meaning "drum") is the semi-circular or triangular decorative wall surface over an entrance, door or window, which is bounded by a lintel and an arch.[1] It often contains pedimental sculpture or other imagery or ornaments.[2] Many architectural styles include this element.[3]
Alternatively, the tympanum may hold an inscription, or in modern times, a clock face.