'unforeseenly-expanded' originates from the combination of 'unforeseenly' and 'expanded'. 'Unforeseenly' is derived from 'unforeseen', which comes from the prefix 'un-' meaning 'not', and 'foreseen', from 'foresee', meaning 'to see beforehand'. 'Expanded' comes from Latin 'expandere', where 'ex-' meant 'out' and 'pandere' meant 'to spread'.

'Unforeseenly' evolved from the Old English 'unforseon', and 'expanded' from the Latin 'expandere', through Middle English 'expanden'.

Initially, 'unforeseenly' meant 'not seen beforehand', and 'expanded' meant 'spread out'. Over time, 'unforeseenly-expanded' came to mean 'expanded in an unexpected manner'.