noun cor·ner·stone \-ˌstōn\

: a stone that forms part of a corner in the outside wall of a building and that often shows the date when the building was built

: something of basic importance

Full Definition of CORNERSTONE

:  a stone forming a part of a corner or angle in a wall; specifically :  such a stone laid at a formal ceremony
:  a basic element :  foundation <a cornerstone of foreign policy>


  1. Officials held a ceremony to lay the cornerstone for a new library.
  2. Trust is the cornerstone of their relationship.

First Known Use of CORNERSTONE

13th century

Other Building Terms

batten, cistern, hearth, lath, transom, wainscot


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