'windowless' originates from the English word 'window' combined with the suffix '-less', where 'window' meant 'an opening in a wall for light and air' and '-less' meant 'without'.

'window' changed from the Old Norse word 'vindauga' and eventually became the modern English word 'window'.

Initially, it meant 'without an opening for light and air', and this meaning has largely remained the same in modern usage.