Definition of keystone
- determination, a keystone of the puritan ethic
- —L. S. Lewis
Tourism is the city's economic keystone.
the keystone of his faith
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'keystone.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
: a large stone at the top of an arch that locks the other stones in place
: something on which other things depend for support
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