Quoin

"Quoin" or "coin" refers to a slightly projecting, sometimes rough-finished masonry on the corners of buildings. Architects and builders use quoins to give the impression of strength and firmness to the outline of a building. Rough-finished or rusticated masonry[?] is also frequently used for foundation layers of buildings to give the same impression. Quoinage can be carried out in stone on a stone building, with stone on a predominantly brick building, or by laying brick masonry to give the appearance of blocks at the corner.

See Architecture.