Word Study
linchpin
CIDE DICTIONARY
linchpin, n. [AS. lynis the axletree; akin to D. luns linchpin, OS. lunisa, LG. lunse, G. lÜnse, OHG. lun peg, bolt.].
A pin used to prevent the wheel of a vehicle from sliding off the axletree. [1913 Webster]
OXFORD DICTIONARY
linchpin, n.
1 a pin passed through an axle-end to keep a wheel in position.
2 a person or thing vital to an enterprise, organization, etc.
1 a pin passed through an axle-end to keep a wheel in position.
2 a person or thing vital to an enterprise, organization, etc.
Etymology
ME linch f. OE lynis + PIN
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