key·​stone | \ ˈkē-ˌstōn \

Definition of keystone

1 : the wedge-shaped piece at the crown of an arch that locks the other pieces in place — see arch illustration
2 : something on which associated things depend for support determination, a keystone of the puritan ethic— L. S. Lewis
3 or keystone species : a species of plant or animal that produces a major impact (as by predation) on its ecosystem and is considered essential to maintaining optimum ecosystem function or structure

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Examples of keystone in a Sentence

Tourism is the city's economic keystone. the keystone of his faith

Recent Examples on the Web

Tax cuts, deregulation, the keystone pipeline is being built. Fox News, "Ronna McDaniel: Trump is an asset on the campaign trail," 11 Aug. 2018 In scientific lingo, penguins aren’t a keystone species—one on which other creatures depend for survival. Jo Craven Mcginty, WSJ, "Counting Penguins Isn’t Always Black and White," 2 Nov. 2018 Members are known as Mormons because of the religion’s keystone scripture, the Book of Mormon. Brady Mccombs, USA TODAY, "Thomas S. Monson, president of Mormon church, dies at 90," 3 Jan. 2018 The North Atlantic Treaty Organization, which has been a keystone of global security since its formation in 1949, does not involve a membership that collects dues. W.j. Hennigan, Time, "President Trump Says NATO Allies Owe the U.S. Money. He's Wrong," 11 July 2018 Dodd-Frank was the keystone of Obama’s post-2008 recession measures to prevent another meltdown., "Trump’s trophy case," 15 June 2018 Get ready for a seismic summer, with James and Paul George hitting free agency, plus several other keystones inching closer to the trade market. Lee Jenkins,, "Kevin Durant and the Dagger That Foreshadowed the Broom," 12 June 2018 Remember: Pennsylvania, the keystone of the president’s 2016 victory, will be a battleground in 2018 and 2020. James Hohmann, Washington Post, "The Daily 202: RFK’s speech in apartheid South Africa remains relevant 50 years after his assassination," 5 June 2018 Essential clinical services, such as providing medication to address cravings for opioids, instituting behavioral health counseling, and recommending support groups, are the keystones for successful recovery. Jay Chaudhary, STAT, "Opioid recovery teams benefit from the addition of lawyers," 29 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'keystone.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of keystone

circa 1637, in the meaning defined at sense 1

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Statistics for keystone

Last Updated

8 Feb 2019

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Time Traveler for keystone

The first known use of keystone was circa 1637

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More Definitions for keystone



English Language Learners Definition of keystone

: a large stone at the top of an arch that locks the other stones in place
: something on which other things depend for support


key·​stone | \ ˈkē-ˌstōn \

Kids Definition of keystone

1 : the wedge-shaped piece at the top of an arch that locks the other pieces in place
2 : something on which other things depend for support

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More from Merriam-Webster on keystone

Rhyming Dictionary: Words that rhyme with keystone

Thesaurus: All synonyms and antonyms for keystone

Spanish Central: Translation of keystone

Nglish: Translation of keystone for Spanish Speakers Encyclopedia article about keystone

Comments on keystone

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to express emotion in a dramatic way

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