Linchpin

Linchpin

Noun · /ˈlɪntʃ.pɪn/

Definition

A pin passed through the end of an axle to keep the wheel in place; a person or thing that holds together all the other parts of a complex system and without which it would fail.

Origin

From Old English lynis (axle, linchpin) + pin (a peg). The lynis element derives from a Proto-Germanic root related to the axle. The compound linchpin has been in English since the 14th century in its literal mechanical sense; the figurative sense of a central holding-together element developed in the 20th century.