A fortnight is a unit of time equal to 14
weeks). The word derives from the
Old English: fēowertyne niht, meaning "fourteen nights".
wages and salaries are paid on a fortnightly basis;
 however in North America it is far more common to use the term
biweekly. Neither of these terms should be confused with
semimonthly, which divides a year into exactly 24 periods (12 months × 2), instead of the 26 (≈
52 weeks ÷ 2) of fortnightly/biweekly.