linchpin

Meanings

1. A pin inserted through holes at the end of an axle or shaft, so as to secure a wheel or shaft-mounted device.
2. A central cohesive source of stability and security; a person or thing that is critical to a system or organisation.

1. To adopt as, or serve as, a central cohesive source of stability and security.

Etymology

From Middle English lynspin, compound of lins (“axletree”) and pin, from Old English lynis (“lynchpin”), from Proto-West Germanic *lunis, from Proto-Germanic *lunaz – compare German Lünse and Dutch luns – from Proto-Indo-European. Possible further cognates are Welsh olwyn (“wheel”), Old Armenian ողն (ołn, “back; spine, backbone”) and Sanskrit आणि (āṇí, “lynchpin”). Figurative use attested from the mid-20th century.