quinzane (n.)

also quinzaine, "group of fifteen; period of fifteen days," 1855, in a historical context, from French quinzaine "the number fifteen; a fortnight" (12c.), from quinze "fifteen," from Latin quindecim (see fifteen). In older use, "the fourteenth day after a feast day" (the fifteenth day by inclusive reckoning), mid-15c. French quinze also was the English name of a popular 18th century card game in which the winner was the first to get 15 points or closest to it without going over.