One who supports or sustains a great burden; a chief supporter, a mainstay.

In figurative contexts: a person or thing occupying a high, central, or vital position in something likened to an arch or similar structure.

The chief character in a dramatic work. Hence, in extended use: the leading character, or one of the main characters, in any narrative work, as a…

In the literal etymological sense: Anything which strengthens or supports; a substratum, a firm support or foundation. literal and figurative.

A person who is prominent or influential in a particular field or organization.

(a) = sense A. 4 (also figurative); (b) Sport a player in a central position (cf. sense A. 3c).

A main or large bolt in a central position, esp. a vertical bolt used as a pivot in an axle. Cf. king bolt, n.

a woman who is essential to the success of a group, organization, or operation; cf. kingpin, n. 2a.