noun. undefined

noun. A stone at the corner of a building uniting two intersecting walls; a quoin.

noun. Such a stone, often inscribed, laid at a ceremony marking the origin of a building.

noun. An indispensable and fundamental basis.

noun. 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 other details.

noun. By extension, that which is prominent, fundamental, noteworthy, or central.

noun. a stone at the outer corner of two intersecting masonry walls

noun. the fundamental assumptions from which something is begun or developed or calculated or explained

noun. a stone in the exterior of a large and important building; usually carved with a date and laid with appropriate ceremonies

"That's what prompted President Roosevelt to launch the Social Security system in 1935, to create what he called the cornerstone of a civilized society."

Groundbreaking ceremony  quoin  

stone  

corner-stone  foundation-stone  

bench mark  cardinal point  chief thing  climax  core