linchpin

Meaning

Noun

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

Origin

• From Middle English lynspin, compound of lins and pin, from Old English lynis, from Proto-Germanic *lunaz – compare German Lünse and Dutch luns – from Proto-Indo-European. Possible further cognates are Welsh olwyn, Old Armenian ողն and Sanskrit आणि.