linchpin

/ˈlɪntʃpɪn/
noun
  1. A person or thing that is essential to the success or functioning of something.
    • The team captain was the linchpin of the defense, holding everyone together.
    • Good communication is the linchpin of a healthy relationship.
    • The new software became the linchpin of the company's digital transformation.
  2. A pin passed through the end of an axle to keep a wheel in place.
    • The farmer replaced the linchpin on the wagon wheel before the harvest.
    • He checked each linchpin on the cart to ensure a safe journey.
    • Without the linchpin, the wheel would slide right off the axle.
What does "linchpin" mean? | whatsthatwordmean | whatsthatwordmean