lynchpin

/ˈlɪntʃpɪn/
noun
  1. A person or thing that is essential to the success or existence of something; the most important part holding everything together.
    • The star player is the lynchpin of the team's offense.
    • The new software became the lynchpin of the company's digital transformation.
    • Good communication is the lynchpin of a healthy relationship.
  2. A metal pin used to keep a wheel or other part in position on an axle.
    • He checked each lynchpin to make sure the cart was safe to drive.
    • Without the lynchpin, the axle would slide right off.
    • The mechanic replaced the rusty lynchpin on the wagon wheel.
What does "lynchpin" mean? | whatsthatwordmean | whatsthatwordmean