Definition of keystone
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
Examples of keystone in a Sentence
Tourism is the city's economic keystone.
the keystone of his faith
Recent Examples of keystone from the Web
Mirella Casares has what used to be considered the keystone of economic security: a job.
Degradation of oaks, considered a keystone species, is the top priority of the state's forestry action plan.
Both Keystones are custom kegerators made by Craig Jones.
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.
First Known Use of keystone
KEYSTONE Defined for English Language Learners
Definition of keystone for English Language Learners
: a large stone at the top of an arch that locks the other stones in place
: something on which other things depend for support
KEYSTONE Defined for Kids
Definition of keystone for Students
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 for support
Seen and Heard
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