Outer curve of an arch with a structural or purely decorative function (* arch).

The curve which bounds the upper edge of the arch.

the outer convex side of an arch.

Outer curve of the voussoirs of an arch, normally concentric with the intrados. Also applies to the upper surface of an arch or vault where visible.

The exterior curve that bounds the upper extremities of the arch.

The outer exposed curve of an arch; defines the lower arc of a spandrel.

The outer portion of an arch.

The exterior curve in an arch or vault.

The curved upper or outer surface of n arch