Originally, a solid exterior angle, as of a building; now, commonly, one of the selected pieces of material by which the corner is marked.
- 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.
- Printing 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.