Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “keystone”


noun [C] (IMPORTANT PART)    /ˈkiː.stəʊn/ US  /-stoʊn/
the most important part of a plan, idea, etc. on which everything else dependsImportant and essential thingsInformation and messages
(Definition of keystone noun (IMPORTANT PART) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
Focus on the pronunciation of keystone

More definitions for “keystone”

Definitions of “keystone” in other dictionaries

Translations of “keystone”

Word of the Day


willing to give money, help, kindness, etc., especially more than is usual or expected

Word of the Day


Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More