from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A locking pin inserted in the end of a shaft, as in an axle, to prevent a wheel from slipping off.
- n. A central cohesive element: Reduced spending is the linchpin of their economic program.
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 the GNU version of the Collaborative International Dictionary of English
- n. A pin used to prevent the wheel of a vehicle from sliding off the axletree.
from The Century Dictionary and Cyclopedia
- n. A pin inserted in the spindle of the axle of a vehicle to prevent the wheel from slipping off. Also axle-pin.
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
Middle English linspin : lins, linchpin (from Old English lynis) + pin, pin (from Old English pinn; see pin).(American Heritage® Dictionary of the English Language, Fourth Edition)
Middle English lynspin, compound of lins 'axletree' and pin, from Old English lynis 'linchpin', from Proto-Germanic *luniso (compare German Lünse), from Proto-Indo-European (compare Welsh olwyn 'wheel', Armenian ołn 'shoulder', Sanskrit āṇís). Figurative use attested from the mid-20th century. (Wiktionary)