Triforium \Tri*fo"ri*um\, n. [LL., fr. L. tri- (see {Tri-}) +
foris, pl. fores, a door.] (Arch.)
The gallery or open space between the vaulting and the roof
of the aisles of a church, often forming a rich arcade in the
interior of the church, above the nave arches and below the
clearstory windows.
[1913 Webster]