What is the meaning of Coign?

A projecting corner or angle; a cornerstone.

The keystone of an arch.

A wedge used in typesetting.

A a corner of a crystal formed by the intersection of three or more faces at a point (in crystallography)

An original angular elevation of land around which continental growth has taken place (in geology)

Alternative form of coyn (coin, quoin)

Source: wiktionary.org