A criminal or dishonest person; also a hooked or bent staff (like a shepherd's crook).
From Old Norse 'krokr,' meaning hook or bend. Applied to people as slang for 'bent' person (morally corrupt) in the 1800s.
The connection between 'crook' (the tool) and 'crook' (the criminal) reveals how our language uses physical shapes to describe character—a 'straight' person is honest, a 'bent' person is corrupt, showing morality encoded in geometry.
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