The pin at the centre of the triangle of bowling pins (originally the tallest pin in kayles). Sometimes also the headpin at the apex.
The axis around which steered wheels pivot; a bolt that holds the axis in place—a kingbolt.
The bolt holding together the truck of a roller skate or skateboard.
The pivot or connector between a tractor and trailer in the fifth-wheel coupling of semi-trailer truck.
The most important person in an undertaking or organization.
A pin inserted through holes at the end of an axle or shaft, so as to secure a wheel or shaft-mounted device.
A central cohesive source of stability and security; a person or thing that is critical to a system or organisation.
To adopt as, or serve as, a central cohesive source of stability and security.