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
The auto focus and keystone correction make setup effortless.
—Shubham Yewale, PC Magazine, 16 May 2025
He’s mostly played second base this year with a little third base mixed in, profiling better at the keystone.
—Keith Law, New York Times, 29 Apr. 2025
In short, the necessary ingredients of all-in AI innovation won’t be enmeshed in the AI Continent keystones, which, regrettably, ultimately the restraints and limits on AI will undermine the upbeat and rosy aspirations accordingly.
—Lance Eliot, Forbes.com, 14 Apr. 2025
Shasta Lake, the state’s largest reservoir and the keystone of the federal Central Valley Project, stood at 94% of capacity on Friday, holding 116% of its historical average.
—Sharon Bernstein, Sacbee.com, 11 Apr. 2025
See All Example Sentences for keystone
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Shubham Yewale, PC Magazine, 16 May 2025
He’s mostly played second base this year with a little third base mixed in, profiling better at the keystone.
—Keith Law, New York Times, 29 Apr. 2025
In short, the necessary ingredients of all-in AI innovation won’t be enmeshed in the AI Continent keystones, which, regrettably, ultimately the restraints and limits on AI will undermine the upbeat and rosy aspirations accordingly.
—Lance Eliot, Forbes.com, 14 Apr. 2025
Shasta Lake, the state’s largest reservoir and the keystone of the federal Central Valley Project, stood at 94% of capacity on Friday, holding 116% of its historical average.
—Sharon Bernstein, Sacbee.com, 11 Apr. 2025
See All Example Sentences for keystone
Cite this Entry
“Keystone.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/keystone. Accessed 29 May. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share