From ‘fourteen nights’ to ‘a fortnight’

A fortnight means fourteen days. The word ‘fortnight’ is derived from the old English word ‘fēowertīene niht’ which means ‘fourteen nights’. In the US, ‘two weeks’ is more commonly used instead of ‘a fortnight’.

‘Fortnightly’ is commonly used in the context of payment of salaries. In North America, however, ‘biweekly’ is more frequently used.