keystone

noun

key·​stone ˈkē-ˌstōn 

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

Synonyms

• base
• basis
• bedrock
• bottom
• cornerstone
• footing
• foundation
• ground
• groundwork
• root
• underpinning
• warp
• warp and woof

Examples of keystone in a Sentence

Tourism is the city's economic keystone.

the keystone of his faith

Recent Examples on the Web

Wellness amenities have been a keystone of luxury developments for years—the wealthy are infatuated with health and longevity hacks, after all. —Brooke Seipel, Fortune, 4 Dec. 2024

And so, after decades of protests from the region’s indigenous tribes, California and Oregon issued approval for dam removal to restore habitat for four keystone fish species: Chinook salmon, Coho salmon, Pacific lamprey, and steelhead trout. —Kelly Bastone, Outside Online, 24 Nov. 2024

Modern digital computers end up at the keystone machine level using individual bits that consist of only two possible states. —Lance Eliot, Forbes, 22 Nov. 2024

These paintings are keystone works of Western art, and were at the top of my list of Umbrian must-sees. —Peter Terzian, Travel + Leisure, 17 Oct. 2024

Word History

First Known Use

circa 1637, in the meaning defined at sense 1

Kids 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