Dictionary entry

Linchpin

Webster's Dictionary 1913

Linch″pin′ (lĭnch″pĭn′), 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.