{i} external corner or angle of a wall; cornerstone, stone forming the external angle of a wall
In architecture, both the external corner of a building and, more often, one of the stones used to form that corner. These stones are both structural and decorative in that they often differ in jointing, colour, texture, or size from the masonry of the adjoining walls. Usually quoins are toothed (i.e., set in short courses in a regular pattern of alternating lengths). Such construction dates back to ancient Rome
the keystone of an arch expandable metal or wooden wedge used by printers to lock up a form within a chase
A structural form, usually of masonry, used at the corners of a building for the purpose of reinforcement, frequently imitated for decorative purposes
Wedge set beneath the breech of a gun and moved in or out to adjust elevation It was eventually superseded by the elevating screw Sometimes spelled coin in contemporary works
Originally, a solid exterior angle, as of a building; now, commonly, one of the selected pieces of material by which the corner is marked
One of a series of blocks or block-like components at the corner of a wall; in a masonry wall, its function is to reinforce the corner