/kræŋk/
[noun] A handle or arm that is attached to a shaft and turned in a circle to make a machine work; also used to describe a person with very strong and unusual ideas that most people think are foolish.
The same word that turns an engine once meant a bent, crooked thing — and later became an insult for a twisted mind.
The word 'crank' begins its life in Old English as 'cranc', a term preserved in the compound 'cranc-stæf', meaning a weaving instrument — specifically the bent handle used on a loom to wind thread. The root is deeply Germanic, connected to the Proto-Germanic stem *krankaz, meaning 'bent' or 'crooked'. This same root flows into Old High German as 'kranc', meaning weak or sick, and into Middle Dutch as 'krank', also carrying the sense of illness or frailty — the idea being that something bent or twisted was somehow broken, weakened. The metaphor of physical crookedness bleeding into the idea of weakness is ancient and runs through many Germanic languages like a shared inheritance.
In Middle English, the mechanical sense of 'crank' — a bent arm or handle used to convert rotary motion into linear motion — became firmly established. By the 14th and 15th centuries, craftsmen and engineers were using it to describe the L-shaped or U-shaped devices on mills, lathes, and early machines. The physical image is always the same: something that bends, something that turns by going around a corner. It is a wonderfully honest word, naming the thing by its most visible quality — its crookedness.
The human insult sense arrived much later and came by a more colourful road. By the late 17th century, 'crank' had picked up a slang meaning in English, referring to a person who was mentally 'bent' or 'twisted' — someone whose thinking did not run straight. This was likely reinforced by an older British dialect use of 'cranky', meaning loose, shaky, or unreliable, applied to ships and carts before it was ever applied to people. By the 19th century, especially in American English, a 'crank' had settled into its modern meaning: someone who holds stubborn, eccentric opinions and refuses to let them go, who grinds away at a pet theory like a hand turning a handle endlessly.
The verb 'to crank' — meaning to turn or start by rotating a handle — emerged naturally from the mechanical noun and became especially common in the early 20th century with the arrival of the automobile. Early cars had to be started by physically turning a crank at the front of the engine, a task that was both laborious and occasionally dangerous, since the handle could kick back and break a wrist. The phrase 'crank it up', meaning to increase power or intensity, grew directly from this image of turning a mechanical handle to get something going.
What makes 'crank' so remarkable is how a single, simple physical image — a bent, turning arm — has branched into such different human territories: machinery, personality, illness, and even drug slang, since 'crank' became American street slang for methamphetamine in the late 20th century, presumably from the stimulant's ability to make users feel 'wound up'. From an Old English loom handle to a modern insult for an obsessive internet commenter, the word has kept its essential character across more than a thousand years: something bent, something turning, something that won't stop going around.