'unimpaired' originates from the prefix 'un-' meaning 'not' and the word 'impaired' from Latin 'impairare', where 'in-' meant 'not' and 'pejorare' meant 'to make worse'.

'impairare' transformed into the Old French word 'empeirer', and eventually became the modern English word 'impaired', with 'un-' added to form 'unimpaired'.

Initially, 'impaired' meant 'to make worse', but 'unimpaired' has always meant 'not damaged or weakened'.