late 13c., from corner (n.) + stone (n.). The figurative use is from early 14c. I endorse without reserve the much abused sentiment of Governor M'Duffie, that "Slavery is the corner-stone of [..]

Category name given to the European Space Agency's key missions in its long-term space science programmes Horizon 2000 and Horizon 2000+.

a quoin or cornerstone, of great importance in binding together the sides of a building. The phrase "corner-stone" is sometimes used to denote any principal person, as the princes of Egypt, [..]

A stone forming a part of a corner or angle in a wall. Also a stone laid at the formal inauguration of the erection of a building.

small contrasting square at the corners of the sashing

(n) the fundamental assumptions from which something is begun or developed or calculated or explained(n) a stone in the exterior of a large and important building; usually carved with a date and laid [..]

A ceremonial stone set at the corner of a building, joining two exterior walls, and often inscribed with the starting and completion dates of construction, the name of the architect and owner, and o [..]