Is it ensure, insure, or assure?
c.1200, from Old French novembre and directly from Latin November (also Novembris (mensis)), from novem "nine" (see nine). The ninth month of the Roman calendar, which began in March. For -ber see December. In Old English, it was Blotmonað "month of sacrifice," literally "blood-month," the time when the early Saxons prepared for winter by sacrificing animals, which they then butchered and stored for food.
11th month of the Gregorian calendar. Its name is derived from novem, Latin for "nine," an indication of its position in the early Roman calendar.