vault

The vault of a Gothic cathedral rests on a series of arches that cross at the summit of the nave and are supported by lateral pillars.

diagonal buttress

Arch connecting two of the vault’s corners through the keystone; it is also called an ogive.

tierceron

Rib connected to a lierne but not to the keystone.

lierne

Rib connecting the top of the tierceron to the keystone.

keystone

Wedge-shaped stone above the nave where the arches meet; it supports the arches and stabilizes the overall structure.

formeret

Arch that supports the vault and is parallel to the axis of the nave.

traverse arch

Arch that supports the vault and is perpendicular to the axis of the nave.