cornerstone

Plural: cornerstones

Noun

• the fundamental assumptions from which something is begun or developed or calculated or explained
• a stone in the exterior of a large and important building; usually carved with a date and laid with appropriate ceremonies
• a stone at the outer corner of two intersecting masonry walls
• A stone forming the base at the corner of a building.
• Such a stone used ceremonially, often inscribed with the architect's and owner's names, dates and other details.
• That which is prominent, fundamental, noteworthy, or central.

Examples

• Exceptional service is the cornerstone of the hospitality industry.
• That is the cornerstone of any meaningful debate about budgets and projects, regulations and policies.
• The cornerstone on the Flatiron Building is set on the Fifth Avenue facade.

Synonyms

base, basis, foundation, fundament, groundwork