1an external angle of a wall or building: smaller stations followed the same pattern; stone-built, with strongly accented quoins (also quoin stone) any of the stones or bricks forming a quoin; a cornerstone. 2 Printing a wedge or expanding mechanical device used for locking a letterpress forme into a chase.
3a wedge for raising the level of a gun barrel or for keeping it from rolling. 1provide (a wall) with quoins or corners: the white plaster walls quoined with red sandstone blocks
2 Printing lock up (a forme) with a quoin.