Definition of "quoin" []

• An exterior angle of a wall or other piece of masonry. (noun)
• 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. (noun)
• A keystone. (noun)
• Printing A wedge-shaped block used to lock type in a chase. (noun)
• A wedge used to raise the level of a gun. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "A quoin is a solid which differs from a wedge in having its sharp end formed by the steep inclination of one side, instead of the mutual tapering of both sides."
• "The figure 8 represents what is called a quoin, and keeps the bolster in its place."
• "The two inner sides of each pair of skill facets form the half of a diamond or lozenge-shaped facet, called a "quoin," of which there are four."