linchpin

IPA/ˈlɪntʃpɪn/
KK[lˈɪntʃpˌɪn]IPA/ˈlɪntʃpɪn/

linchpin — noun

1. the person or thing a team, plan, or system depends on most; without it, the res

1.nounC1
Definition

the person or thing a team, plan, or system depends on most; without it, the rest cannot keep working well.

Example

Nkechi is the linchpin of the clinic, keeping doctors, drivers, and supplies moving on time.

the linchpin of [organization]

Without Samir, the small design team loses its linchpin and misses every project deadline.

lose its linchpin + breakdown

Common collocations
  • the linchpin of the team
  • the linchpin of the plan
  • the linchpin of the system
Synonyms
  • keystone

    often stresses the piece that locks a structure together

  • cornerstone

    more often used for a founding value or first principle

  • backbone

    emphasizes strength and steady support rather than one removable part

Grammar Patterns

the linchpin of [team/plan/system]

Usage Note

Usually appears in phrases like 'the linchpin of the team' or 'the linchpin of the plan' and often refers to one person or one central feature. Distinguish from sense 2, which names a real metal pin on a wheel or axle.

2. a small metal pin fixed across an axle's end so a wheel cannot slide off.

2.nounC2
Definition

a small metal pin fixed across an axle's end so a wheel cannot slide off.

Example

Theo checked the tractor's linchpin before towing the trailer across the muddy field.

check the linchpin before towing

One loose linchpin let the cart wheel slide off halfway down the farm road.

loose linchpin + wheel slide off

Common collocations
  • remove the linchpin
  • replace the linchpin
  • the wheel's linchpin
Synonyms
  • axle pin

    a broad mechanical term for a pin used on an axle

  • locking pin

    more general and not limited to wheels or axles

Grammar Patterns

remove the linchpin from [wheel/axle]

Usage Note

Mostly used in mechanical or farming contexts with wheels, carts, trailers, or axles. In ordinary figurative English, people usually mean sense 1 instead.

Common Mistakes

The linchpin goes inside the tire.
The linchpin goes through the axle end.
it locks the wheel onto the axle rather than sitting in the rubber tire.

Synonym discussion

Sense: noun/1

All four words describe something essential, but they highlight different roles. A linchpin is the one person or part the whole system depends on; if you remove it, work quickly breaks down. A keystone keeps the image of an arch and often stresses the piece that locks a structure together. A cornerstone is the founding base or principle you build from, especially in plans or values. Backbone usually suggests strength and steady support rather than one removable part. Use linchpin when one missing person or feature would make the rest stop working.

linchpin ↗keystone ↗cornerstone ↗backbone

Common collocations

Nouns

  • the linchpin of the team
  • the linchpin of the plan
  • the linchpin of the system
  • the linchpin of the campaign

Phrases

  • be the linchpin
  • become the linchpin
  • remove the linchpin

Prepositions

  • linchpin of

Etymology

English

The literal meaning came first: a metal pin that keeps a wheel fixed on its axle. From that image, English later developed the figurative sense for a person or feature that keeps a larger group, plan, or system from falling apart.