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

Its automatic keystone correction adjusts the display for proper alignment from any angle, simplifying setup in any environment. —Stackcommerce Team (sponsored), PCMAG, 14 Jan. 2025

The all-in-one projector will handle the rest of the fine-tuning, including focus, optical zoom, and keystone adjustments to ensure the image is level and perfectly aligned. —Andrew Liszewski, The Verge, 3 Jan. 2025

For more on various keystone prompting strategies and techniques, see my comprehensive review at the link here. —Lance Eliot, Forbes, 1 Dec. 2024

The keystone in the domino chain to stardom was the Barbra Streisand version of A Star Is Born, in 1976. —Matt Zoller Seitz, Vulture, 1 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