'unforeseeably-extended' originates from the combination of 'unforeseeable' and 'extended', where 'unforeseeable' is derived from 'un-' meaning 'not' and 'foresee' meaning 'to see beforehand', and 'extended' from 'extend' meaning 'to stretch out'.

'unforeseeably-extended' combines the adverb 'unforeseeably' with the adjective 'extended', evolving from the base verb 'extend'.

Initially, 'extend' meant 'to stretch out', but in this context, it evolved to mean 'prolonged in an unexpected manner'.