'sightlessness' originates from the Old English word 'sihþ,' where 'sight' meant 'the ability to see,' combined with the suffix '-less,' indicating absence.

'sihþ' transformed into the Middle English word 'sight,' and eventually became the modern English word 'sightlessness' by adding the suffix '-ness' to indicate a state or condition.

Initially, it meant 'the state of not having sight,' and this meaning has largely remained the same in modern usage.