The definition of a fortnight is a two-week period of time.(noun)
Many British Commonwealth countries pay employees every two weeks, an example of a fortnight-based payroll system.
See fortnight in Webster's New World College Dictionary
Origin: ME fourte(n) niht < OE feowertyn niht, lit., fourteen nights
See fortnight in American Heritage Dictionary 4
Origin: Middle English fourtenight
Origin: , alteration of fourtene night, fourteen nights
Origin: : Old English fēowertēne, fourteen; see kwetwer- in Indo-European roots
Origin: + Old English niht, night; see nokwt- in Indo-European roots.
Learn more about fortnight