quoin

An exterior angle of a wall or other piece of masonry.

Any of the stones used in forming such an angle, often being of large size and dressed or arranged so as to form a decorative contrast with the adjoining walls.

A keystone.

A wedge-shaped block used to lock type in a chase.

A wedge used to raise the level of a gun.

To provide, secure, or raise with a quoin or quoins.

To wedge, steady, or raise with quoins, as a stone in building a wall, the types in a chase, etc.: generally with up. See quoin, n., 2.

The solid angle of a crystal in which three or more faces meet. Also written coign.

An external solid angle; specifically, in architecture and masonry, the external angle of a building.