the.com/lynchpin
The one piece that, pulled, turns a wheel into a pile of wheel parts.
means The small but critical part or person holding an entire system together, without which everything else falls apart.
from Properly spelled 'linchpin,' it's a wheelwright's term: the 'linch' (from Old English 'lynis,' meaning axle-pin) is the metal pin pushed through the end of an axle to stop the wheel sliding off. The spelling 'lynchpin' is a common modern confusion with 'lynch' (the mob-violence word, from a different, unrelated American source) — same sound, totally separate history, but the misspelling has become widespread enough to feel almost standard.
- actual spelling
- linchpin is correct, lynchpin is a common drift
- origin
- a literal pin locking a wagon wheel to its axle
- metaphor jump
- 18th century writers started using it for essential people
- irony
- the word itself gets misspelled constantly, unlike its meaning