The negative form of 'can,' meaning to be unable to do something or to have no permission to do something.
Historically 'can not' (two words), but 'cannot' merged into one word by the 1600s; 'can' comes from Old English 'cunnan' (to know or be able), and 'not' is the standard negation.
English is weird because we write 'cannot' as one word, but 'can not' is rare—yet we split almost every other auxiliary negative like 'do not,' 'will not,' showing inconsistent spelling rules evolved randomly over time.
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