Definitions

1. noun

a wedge-shaped stone, typically of limestone, used as the central stone in an arch or vault, supporting the weight of the structure above it.

“The keystone of the ancient Roman bridge held the structure together for centuries.”

2. noun

an essential or crucial element or factor in a system, organization, or situation.

“Her creativity was the keystone of the company’s innovative product development.”

3. verb

to use or provide the keystone to support or hold something in place.

“The masons keystoneed the arch with a precise and carefully cut stone.”