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
L. S. Lewis3
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
Sometimes these environmental disintegrations can be subtle, like the slow decline of an endangered keystone species or the gradual weakening of ocean currents.
—Darren Orf, Smithsonian Magazine, 18 Mar. 2025
As with most newer competition, the C2 Ultra includes a full set of automatic adjustment features for quick setup, including autofocus, keystone correction, and obstacle avoidance.
—PCMAG, 12 Mar. 2025
Right now though, movie watchers can look forward to 95% coverage of the DCI-P3 color gamut, while setup flexibility is helped along by keystone correction, 1.6x zoom, and vertical/horizontal lens shift.
—Paul Ridden, New Atlas, 4 Mar. 2025
Boston’s Bonanza The Boston Red Sox have two in second baseman Kristian Campbell and outfielder Roman Anthony but the former could be blocked if Alex Bregman, signed as a free agent, shifts from third base, his position in Houston, to the keystone.
—Dan Schlossberg, Forbes, 21 Feb. 2025
See All Example Sentences for keystone
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Darren Orf, Smithsonian Magazine, 18 Mar. 2025
As with most newer competition, the C2 Ultra includes a full set of automatic adjustment features for quick setup, including autofocus, keystone correction, and obstacle avoidance.
—PCMAG, 12 Mar. 2025
Right now though, movie watchers can look forward to 95% coverage of the DCI-P3 color gamut, while setup flexibility is helped along by keystone correction, 1.6x zoom, and vertical/horizontal lens shift.
—Paul Ridden, New Atlas, 4 Mar. 2025
Boston’s Bonanza The Boston Red Sox have two in second baseman Kristian Campbell and outfielder Roman Anthony but the former could be blocked if Alex Bregman, signed as a free agent, shifts from third base, his position in Houston, to the keystone.
—Dan Schlossberg, Forbes, 21 Feb. 2025
See All Example Sentences for keystone
Articles Related to keystone
Cite this Entry
“Keystone.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/keystone. Accessed 25 Mar. 2025.
Copy CitationKids Definition
keystone
noun
key·stone
ˈkē-ˌstōn 
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
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