key·​stone | \ ˈkē-ˌstōn How to pronounce keystone (audio) \

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 Atlanta, for example, is a hip-hop keystone known as the home of trap music, but new waves of talent, as disparate as J.I.D and Playboi Carti, are experimenting with mood and content. Mankaprr Conteh, Rolling Stone, "Kenny Mason Raps as Well as He Rocks," 15 Apr. 2021 Beavers are considered a keystone species that helps the overall health of stream ecosystems, so the reintroduction plan was carried out by the federal Bureau of Land Management with the involvement of Arizona’s Game and Fish Department. Ian James, The Arizona Republic, "'It's so cool to see': Building dams by night, beavers resurface along Arizona's San Pedro River," 9 Apr. 2021 Today, the walking memoir — in which the main character chronicles his amblings, making mundane observations and grandiose discoveries along the way — is a significant subgenre, with Kazin’s book as its keystone work. Washington Post, "Alfred Kazin’s “A Walker in the City” charts an intellectual awakening, block by block," 4 Mar. 2021 With the deepening financial crisis of COVID-19, and despite its size and role as a keystone for Central Florida’s economy and employment, Orlando International Airport’s oversight leadership has dwindled from seven to four members. Kevin Spear,, "Orlando airport leadership shrinks as COVID challenges grow," 14 Aug. 2020 However, keystone typically involves multiple revenue streams, which is where the complexity lies. Dan Brown, Forbes, "How B2B Companies Can Solve The Keystone Problem," 26 Feb. 2021 Back in 2001, Watson made the case in an article in the Annual Review of Ecology and Systematics that mistletoes are keystone species on which much of the life surrounding them depends. Rachel Ehrenberg, Smithsonian Magazine, "The Biology of Mistletoe," 23 Dec. 2020 Careerism, not community, is the keystone in the arch of life. Derek Thompson, The Atlantic, "How Civilization Broke Our Brains," 13 Dec. 2020 Tegus are also destructive to gopher turtles, a keystone species in Georgia and Florida. Outdoor Life, "Dog-Sized Lizards are Taking Over in the Southern U.S.," 11 Dec. 2020

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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Time Traveler for keystone

Time Traveler

The first known use of keystone was circa 1637

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Statistics for keystone

Last Updated

19 Apr 2021

Cite this Entry

“Keystone.” Dictionary, Merriam-Webster, Accessed 20 Apr. 2021.

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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 How to pronounce keystone (audio) \

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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