- The definition of a fortnight is a two-week period of time.
Many British Commonwealth countries pay employees every two weeks, an example of a fortnight-based payroll system.
fortnight definition by Webster's New World
Origin: Middle English fourte(n) niht ; from Old English feowertyn niht, literally , fourteen nights
fortnight definition by American Heritage Dictionary
Origin: Middle English fourtenight, alteration of fourtene night, fourteen nights : Old English fēowertēne, fourteen; see kwetwer- in Indo-European roots + Old English niht, night; see nokwt- in Indo-European roots.