keystone

3 definitions • 2 examples

the middle stone in the top of an arch that has a special shape and holds all the other stones in position

the most important part of a plan, idea, etc. on which everything else depends

the most important part of a plan, idea, etc. on which everything else depends:

Selling overseas has been, and always will remain, one of the keystones of our national prosperity.

A keystone of its corporate strategy is to invest in people, technology, and training to create a brand.