Fortnight 1 : A traditional English unit of time equal to 2 weeks or 14 days. The word, a contraction of "fourteen nights," has been used since at least the 1100s
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}