kingpins

/K IH1 NG P IH0 N Z/
noun
  1. 1

    (motorized vehicles) The axis around which steered wheels pivot; a bolt that holds the axis in place—a kingbolt.

  2. 2

    The pin at the centre of the triangle of bowling pins (originally the tallest pin in kayles). Sometimes also the headpin at the apex.

  3. 3

    The most important person in an undertaking or organization.

  4. 4

    The bolt holding together the truck of a roller skate or skateboard.

Source: https://en.wiktionary.org/wiki/kingpin, https://en.wiktionary.org/wiki/kingpins