There are 2 definitions of keystone in English:

keystone1

Line breaks: key|stone
Pronunciation: /ˈkiːstəʊn
 
/

noun

1A central stone at the summit of an arch, locking the whole together.
More example sentences
  • The final seven rusticated bands are precisely linked to the voussoirs and keystones that define the arches and the niches, the latter exactly the same height as the rectangular openings below.
  • The windows are surmounted by rusticated wooden jack arches with superimposed keystones, and a heavy modillion cornice crowns the bold Georgian proportions of the facade.
  • With a thickness of 12 inches, the arch features a decorative keystone and double corbels, outlined by antique glazing on a white lacquer base.
Synonyms
1.1The central principle or part of a policy, system, etc., on which all else depends: cooperation remains the keystone of the government’s security policy
More example sentences
  • Property rights, of course, form one of the keystones of the Anglosphere system.
  • This win-win strategy is the keystone of the economic policy framework of the Government.
  • People and the planet on which we live should be the primary referents of security in the 21st century, and human and global security should be the keystones of Australia's foreign and defence policies.
Synonyms
foundation, basis, linchpin, cornerstone, base, principle, guiding principle, core, heart, centre, crux, fundament, mainspring, priority

Definition of keystone in:

Get more from Oxford Dictionaries

Subscribe to remove adverts and access premium resources

Word of the day apposite
Pronunciation: ˈapəzɪt
adjective
apt in the circumstances or relation to something

There are 2 definitions of keystone in English:

Keystone2

Line breaks: Key|stone
Pronunciation: /ˈkiːstəʊn
 
/
A US film company formed in 1912, remembered for its silent slapstick comedy films, many featuring the bumbling Keystone Kops police characters.