Kingpin or king pin may refer to: Vehicular part. Kingpin (automotive part), the pivot in the steering mechanism. The central bolt of a skateboard, axle assembly ("truck"), around which the rest of the mechanism can flex, allowing the rider to steer by shifting body weight. The pivot or connector between a tractor and trailer in the fifth-wheel coupling of semi-trailer truck. The pivot in a railway car bogie. Crime. Crime boss, in organized crime. Drug lord, a type of crime boss. Literature. Kingpin (book), written by former hacker Kevin Poulsen.
https://en.wikipedia.org/wiki/Kingpin