1. In a classical-style building, the triangular segment between the horizontal entablature and the sloping roof.
2. (Gr. ἀετός, Lat. fastigium, Fr. ponton), in classic architecture the triangular-shaped portion of the wall above the cornice which formed the termination of the roof behind it. The projecting mouldings of the cornice which surround it enclose the tympanum, which is sometimes decorated with sculpture.