1. a person or thing that is essential to the success or functioning of something
Usage: figurative
2. a metal pin that passes through the end of an axle to keep a wheel in position
Usage: mechanical; literal

Examples

• The quarterback is the linchpin of our football team.
• She became the linchpin of the entire marketing campaign.
• Without proper funding, the linchpin of the project collapsed.
• The mechanic replaced the broken linchpin on the wagon wheel.
• Trust is the linchpin of any successful relationship.
• The linchpin held the wheel securely to the axle.
• He was considered the linchpin of the company’s success.