from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Variant of linchpin.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a pin inserted through holes at the end of an axle, so as to secure a wheel
- n. a central cohesive source of stability and security; a person or thing that is critical to a system or organisation.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. pin inserted through an axletree to hold a wheel on
- n. a central cohesive source of support and stability
From Middle English lynspin, from Old English lynis (a pin securing a wheel to an axle). Figurative use attested from the mid 20th Century. (Wiktionary)