A fortnight is a unit of time equal to 14 days (two weeks). The word derives from the Old English term fēowertīene niht, meaning "fourteen nights" (or "fourteen days", since the Anglo-Saxons counted by nights).[1][2]
^"Fortnight". The Concise Oxford Dictionary (5th ed.). 1964. p. 480.
^Senight, sennight or se'night (seven-night), an old word for the week, was still in use in the early 19th century, to judge from Jane Austen's letters.