lancet: A slender, pointed window.

See also mullion

lantern: A small circular or polygonal structure, with windows all around the base, which opens above a larger tower or dome.

Latin coss :A cross with three short arms and one long arm.

Compare with Greek cross

lierne: A minor rib in a complex rib vault. Liernes do not spring from the main springers.

Other types of ribs: diagonal, ridge,tierceron, transverse

See also rib vault, springer

linenfold: decorative motif in the form of a folded piece of linen cloth. usually carved in low relief.

lintel:A flat horizontal beam which spans the space between two supports.

loggia: An exterior gallery, open on one or more sides, with a colonnade or an arcade.

longitudinal barrel vault: a barrel (or tunnel) vault which follows the main longitudinal direction of the nave. Usually when a vault is referred to simply as a barrel (or tunnel) vault, it may be assumed to be a longitudinal barrel vault.

See also: barrel vault, groin vault

longitudinal ridge rib or ridge rib: A rib which runs down the apex of the vault in a longitudinal direction.

Other types of ribs: diagonal, lierne,tierceron, transverse
See also rib vault
lozenge: A diamond shape.
See also other repetative decorative motifs