key·​stone ˈkē-ˌstōn How to pronounce keystone (audio)
: the wedge-shaped piece at the crown of an arch that locks the other pieces in place see arch illustration
: something on which associated things depend for support
determination, a keystone of the puritan ethicL. S. Lewis
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

Examples of keystone in a Sentence

Tourism is the city's economic keystone. the keystone of his faith
Recent Examples on the Web For the keystones about prompting of personas in generative AI, see the link here and the link here. Lance Eliot, Forbes, 11 Feb. 2024 These Falcon Heavy flights will cut across NASA's portfolio of robotic space missions, dispatching probes deep into the Solar System, deploying a flagship-class astronomical observatory, sending up a weather satellite, and launching the keystone to NASA's Gateway mini-space station around the Moon. Stephen Clark, Ars Technica, 13 Oct. 2023 Taken altogether, the speaker lineup might indicate a returning interest in third-party licensing, as keystone studios look to juice sales revenue, complementing the B2C model rather than competing with it. Ben Croll, Variety, 12 Oct. 2023 The rollback also comes as political campaigning for the United States 2024 presidential election ramps up, and concerns about the spread of misinformation online remains a keystone issue ahead of the US vote. Catherine Thorbecke, CNN, 27 Sep. 2023 Early childhood development has long been a keystone of Princess Kate’s royal world, and her back-to-back engagements shed light on the importance of loving relationships for children who have experienced adversity, trauma, or bereavement. Janine Henni, Peoplemag, 25 May 2023 The Oscars are recognized by moviegoers around the world as the pinnacle of artistic accomplishment in motion pictures, and this important step, taken by the Academy, affirms that theatrical exhibition is the keystone of the industry. Scott Feinberg, The Hollywood Reporter, 21 June 2023 This pay-to-play standard is the basis of the North American model of wildlife conservation, which is the popular set of principles that honors hunting, fishing, and trapping as a keystone of modern wildlife management in the U.S. Katie Hill, Outdoor Life, 29 Nov. 2023 How exactly Earth’s sunward sister world went so far astray is one of the greatest mysteries of planetary science—and a potential keystone for astrobiology. Leonard David, Scientific American, 14 Nov. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'keystone.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

circa 1637, in the meaning defined at sense 1

Time Traveler
The first known use of keystone was circa 1637

Dictionary Entries Near keystone

Cite this Entry

“Keystone.” Dictionary, Merriam-Webster, Accessed 23 Feb. 2024.

Kids Definition


key·​stone ˈkē-ˌstōn How to pronounce keystone (audio)
: the wedge-shaped piece at the top of an arch that locks the other pieces in place
: something on which other things depend

More from Merriam-Webster on keystone

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