cornerstone

American  

[kawr-ner-stohn] / ˈkɔr nərˌstoʊn /

noun

cornerstones plural

1. a stone uniting two masonry walls at an intersection.

2. a stone representing the nominal starting place in the construction of a monumental building, usually carved with the date and laid with appropriate ceremonies.

3. something that is essential, indispensable, or basic.

   The cornerstone of democratic government is a free press.

4. the chief foundation on which something is constructed or developed.

   The cornerstone of his argument was that all people are created equal.

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cornerstone British  

/ ˈkɔːnəˌstəʊn /

noun

1. a stone at the corner of a wall, uniting two intersecting walls; quoin

2. a stone placed at the corner of a building during a ceremony to mark the start of construction

3. a person or thing of prime importance; basis

   the cornerstone of the whole argument

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Other Word Forms

Noun Inflected Forms

• cornerstones
  plural

Etymology

Origin of cornerstone

Middle English word dating back to 1250–1300; see origin at corner, stone

Explanation

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.

Example Sentences

See Examples For:

cornerstone cornerstones

This is not just one part of American history but a cornerstone of it.

From Slate ● Jul. 20, 2026

"The Odyssey" is an Ancient Greek poem believed to have been written by Homer that is considered a cornerstone of Western literature and one of the finest stories ever created.

From Barron's ● Jul. 10, 2026

Nato, the cornerstone of Western nations' defence, is stronger than ever.

From BBC ● Jul. 8, 2026

“It is,” says Tom Stevens, director of Visitor Services, “the cornerstone of the Rotunda.”

From The Wall Street Journal ● Jul. 4, 2026

“Alar is the cornerstone of sympathy. If you are going to impose your will on the world, you must have control over what you believe.”

From "The Name of the Wind" by Patrick Rothfuss

The King spelt out the cornerstones: there had to be support for Nato, "keeping North Americans and Europeans safe from our common adversaries".

From BBC ● Apr. 28, 2026

Homeownership is one of the cornerstones of the American dream, deeply ingrained in our culture as a symbol of financial success and stability.

From MarketWatch ● Apr. 24, 2026

The Green Bay Packers were formed a year later, and the two institutions, about five miles apart, grew up side by side as cornerstones of the community.

From Salon ● Mar. 10, 2026

Carney has made boosting commerce with Europe and Asia cornerstones of his strategy to backstop Canada's economy, should free trade with Washington collapse.

From Barron's ● Feb. 26, 2026

The cornerstones of this country’s operation are economic and political strength and power.

From "The Autobiography of Malcolm X" by Alex Malcolm X;Hailey

Related Words

• essential
• foundation
• keystone
• linchpin
• mainstay
• pillar