In the Nick of Time

A "nick" was originally a small notch or groove cut into a stick or tally board, a common, everyday way of keeping records before widespread literacy, used by merchants, gamblers, and timekeepers alike to mark an exact point, a score, or a precise moment. "In the nick" meant at that exact, pinpoint instant, a sense documented from the 16th century. "Of time" was added later, spelling out the meaning more explicitly, and the full phrase as we use it today is documented in English from 1643 onward.