'unsettle' originates from the prefix 'un-' meaning 'not' and the word 'settle', which comes from Old English 'setlan', meaning 'to place or arrange'.

'setlan' transformed into the Middle English word 'setlen', and eventually became the modern English word 'settle'.

Initially, 'settle' meant 'to place or arrange', but 'unsettle' evolved to mean 'to disturb or make uneasy'.