'unforeseeable' originates from the prefix 'un-' meaning 'not' and the word 'foreseeable,' which comes from 'foresee,' meaning 'to see or know beforehand.'

'foresee' changed from the Old English word 'foreseon' and eventually became the modern English word 'foresee.'

Initially, it meant 'to see or know beforehand,' and this meaning has largely remained the same in modern usage.