cornerstone

/ˌkɔrnərˈstoʊn/

/ˈkɔnəstəʊn/

Other forms: cornerstones

A cornerstone is literally a stone at the corner of a building. It’s an important stone, so it also means “the basic part of something,” as in, the cornerstone of the suffragette movement was getting women the right to vote.

When a building goes up, putting in the cornerstone is a big deal and people celebrate. Many cornerstones are engraved with historical information about the building, such as the year the building was built. The cornerstone is sometimes made of a different material from the rest of the building too. From the sense of "foundation," cornerstone also means "essential element.” If you’re really into Italian food, you might say that pasta is the cornerstone of your diet.

Definitions of cornerstone

1. noun

   the fundamental assumptions from which something is begun or developed or calculated or explained
   synonyms: base, basis, foundation, fundament, groundwork

   types:

   meat and potatoes

   the fundamental part

   type of:

   assumption, supposal, supposition

   a hypothesis that is taken for granted
2. noun

   a stone at the outer corner of two intersecting masonry walls
   type of:

   stone

   building material consisting of a piece of rock hewn in a definite shape for a special purpose
3. noun

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

   stone

   building material consisting of a piece of rock hewn in a definite shape for a special purpose