Definition of linchpin
1 : a locking pin inserted crosswise (as through the end of an axle or shaft)
2 : one that serves to hold together parts or elements that exist or function as a unit <the linchpin in the defense's case>
Examples of linchpin in a sentence
This witness is the linchpin of the defense's case.
Did You Know?
There was the good old custom of taking the linch-pins out of the farmers' and bagmens' gigs at the fairs, and a cowardly blackguard custom it was. That custom, described by British writer Thomas Hughes in his 1857 novel Tom Brown's School Days, was "blackguard" indeed. The linchpin in question held the wheel on the carriage and removing it made it likely that the wheel would come off as the vehicle moved. Such a pin was called a "lynis" in Old English; Middle English speakers added "pin" to form "lynspin." Modern English speakers modified it to "linchpin" and, in the mid-20th century, began using the term figuratively for anything as critical to a complex situation as a linchpin is to a wagon.
Origin and Etymology of linchpin
Middle English lynspin, from lyns linchpin (from Old English lynis) + pin; akin to Middle High German luns linchpin
First Known Use: 13th century
LINCHPIN Defined for English Language Learners
Definition of linchpin for English Language Learners
: a person or thing that holds something together : the most important part of a complex situation or system
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