keystone
/ˈkiːstəʊn/ (bre, ipa) · /ˈkiːstəʊn/ (ame, ipa) · /ˈkē-ˌstōn/ (ame, mw)
keystone — noun
- keystonesingular
- keystonesplural
1. the wedge-shaped block placed at the very top of a stone arch, which locks every
the wedge-shaped block placed at the very top of a stone arch, which locks every other block tightly into place.
Gabriel pointed up at the chapel arch and named the carved keystone above the door.
keystone of an arch (literal architectural use)
Without its keystone, the old Roman arch would crumble within minutes under its own weight.
without its keystone + structural consequence
The mason cut the keystone last and slid it into the centre of the bridge arch.
Tourists photograph the carved lion's face on the keystone above the cathedral's main entrance.
Engineers warn that one cracked keystone can bring the entire arch down on the road below.
文法句型
the keystone of [arch/vault]
用法筆記
Only sense that takes a physical preposition like 'above' or 'on'; the second sense is always followed by 'of' plus an abstract noun (a plan, an argument, a policy).
常見錯誤
2. the single element of a plan, argument, or system that holds everything else tog
the single element of a plan, argument, or system that holds everything else together — remove it and the whole structure falls apart.
Affordable childcare became the keystone of the candidate's campaign for working families.
the keystone of [a campaign / policy / plan]
Amira argued that mutual trust is the keystone of every successful long-term business partnership.
X is the keystone of Y (defining the central support)
Once the prosecution's main witness changed her story, the keystone of the case quietly fell away.
For Defne, weekly family dinners are the keystone that keeps her three grown children close.
Reliable rainfall is the keystone of farming in this valley; one dry summer ruins the whole harvest.
- cornerstone
near-synonym; cornerstone is the foundation you build up from, keystone is the piece at the top that locks everything else
- linchpin
more informal; emphasises that removing this part causes immediate collapse
- lynchpin
British spelling variant of linchpin; same meaning
文法句型
the keystone of [plan/argument/policy]
用法筆記
Almost always 'the keystone of X' with a singular noun phrase; saying 'a keystone' weakens the meaning because by definition there is only one central support. Distinguish from sense 1 by the abstract object — plans, arguments, policies, partnerships, never physical stones.