/koyn, kwoyn/ , n.
1. an external solid angle of a wall or the like.
2. one of the stones forming it; cornerstone.
3. any of various bricks of standard shape for forming corners of brick walls or the like.
4. a wedge-shaped piece of wood, stone, or other material, used for any of various purposes.
5. Print. a wedge of wood or metal for securing type in a chase.
v.t.
6. to provide with quoins, as a corner of a wall.
7. to secure or raise with a quoin or wedge.
Also, coign, coigne .
[ 1525-35; var. of COIN ]