Definition of "linchpin" in English

noun

1. A pin inserted through holes at the end of an axle or shaft, so as to secure a wheel or shaft-mounted device.

   • In ij camellis ferri vocatis lynspins emptis pro carectis iiijᵈ.

2. (figuratively) A central cohesive source of stability and security; a person or thing that is critical to a system or organisation.

verb

1. (ambitransitive) To adopt as, or serve as, a central cohesive source of stability and security.