quoin

1. (printing, historical) A metal wedge which fits into the space between the type and the edge of a chase, and is tightened to fix the metal type in place.Examples: "Next fit the quoins, using the “persuader” to squeeze in the pages, and tap up all around."historical

2. (obsolete, nautical) A form of wedge used to prevent casks from moving.obsolete

3. (firearms) A wedge of wood or iron put under the breech of heavy guns or the muzzle of siege-mortars to raise them to the proper level.

4. (horticulture) A number of apple varieties with a distinctive ribbed appearance, like corners of a coin.