Coign is an older spelling of Quoin, and may refer to:
Coign (architecture), masonry blocks at the corner of a wall Coign (gunnery), a wedge used in aiming a cannon Coign (printing), wooden or metal wedges used for locking printing type into a chase A coign, in Crystallography, is the point at which three facets of a crystal meet A coign, in Geology, is an angular plate around which a continent has formed
See also Coign of vantage, an elevated observation point Coign and livery, military exactions in Gaelic Ireland