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

For years, Goretzka was a cornerstone of Bayern Munich's midfield.

From BBC ● Aug. 27, 2026

Google bought British AI lab DeepMind about 12 years ago, and the business unit it led to is now the cornerstone of its AI efforts.

From The Wall Street Journal ● Aug. 25, 2026

It was the latest jolt to South Korea’s confidence in an alliance that has formed a cornerstone of Washington’s defense strategy in Asia since the end of World War II.

From Los Angeles Times ● Aug. 19, 2026

It was also a cornerstone investor in SK Hynix’s recent U.S. debut.

From MarketWatch ● Jul. 31, 2026

“Oh, not too long ago,” said Kojo, pointing to the marble cornerstone.

From "The Smartest Kid in the Universe" by Chris Grabenstein

Spiritual jazz and psychedelic soul are cornerstones of her sound, along with new-age accouterments like prayer bowls and chimes blended with instruments including Fender Rhodes keyboards and vibraphone.

From The Wall Street Journal ● Sep. 1, 2026

As tech has grown as an overwhelming force in our lives, the visual design cornerstones associated with it—arial font, minimalist branding, bright colors and clean lines—have become the norm.

From Slate ● Aug. 21, 2026

Throw in the likelihood that Mark Wood will never play another Test and it means the four cornerstones of England's pace attack have gone in the space of three years, taking 1,609 wickets with them.

From BBC ● Jun. 4, 2026

This devotion to authenticity is one of Thompson’s cornerstones.

From Salon ● May 15, 2026

Apart from the Suppression of Communism Act, two laws passed in 1950 formed the cornerstones of apartheid: the Population Registration Act and the Group Areas Act.

From "Long Walk to Freedom" by Nelson Mandela

Related Words

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