Definition from Wiktionary, the free dictionary
cornerstone (plural cornerstones)
- 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.
- The cornerstone on the Flatiron Building is set on the Fifth Avenue facade.
- By extension, that which is prominent, fundamental, noteworthy, or central.
- Exceptional service is the cornerstone of the hospitality industry.
- That is the cornerstone of any meaningful debate about budgets and projects, regulations and policies.
that which is prominent, fundamental, noteworthy, or central