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
Setup is effortless with auto-focus and auto-keystone, while Dolby Audio dual speakers provide immersive sound.
—Juhi Wadia, PC Magazine, 20 Apr. 2026
Kim learned that beavers are a keystone species — an organism that holds an ecosystem together.
—Elizabeth Hernandez, Denver Post, 16 Apr. 2026
In January of 2022, the brand purchased sponsor rights to Chase Field’s keystone feature, then branded it as the Cremily Pool Suite.
—Sam Blum, New York Times, 13 Apr. 2026
The Fort Worth City Council approved a 121-acre data center project, a keystone of the 1,756-acre Rock Creek Ranch development, during a September 2024 meeting.
—Samuel O’Neal 8, Fort Worth Star-Telegram, 8 Apr. 2026
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.
Juhi Wadia, PC Magazine, 20 Apr. 2026
Kim learned that beavers are a keystone species — an organism that holds an ecosystem together.
—Elizabeth Hernandez, Denver Post, 16 Apr. 2026
In January of 2022, the brand purchased sponsor rights to Chase Field’s keystone feature, then branded it as the Cremily Pool Suite.
—Sam Blum, New York Times, 13 Apr. 2026
The Fort Worth City Council approved a 121-acre data center project, a keystone of the 1,756-acre Rock Creek Ranch development, during a September 2024 meeting.
—Samuel O’Neal 8, Fort Worth Star-Telegram, 8 Apr. 2026
See All Example Sentences for keystone
Cite this Entry
“Keystone.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/keystone. Accessed 27 Apr. 2026.
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
