noun

keystone

KEE-stohn

noun

The central wedge-shaped stone at the top of an arch that locks the other stones in place.

"Remove the keystone and the whole arch collapses."

The central element that everything else depends on or is built around.

"Trust is the keystone of any good relationship."

How to Use Keystone

Learner’s notes

In plain EnglishLiterally the locking stone at the top of an arch, or figuratively the single most essential part of a plan, argument, or system.

Common pairings

keystone of the arch keystone species keystone policy

keystoned past tense, keystones plural, keystones singular

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Can you complete this real example?

Remove the _____ and the whole arch collapses.

From "key" (in the sense of a locking piece) and "stone" — the stone that locks an arch together.

one bone done gone none tone lone hone cone zone Sone stone