November (Roman month) November (Roman month) November (from Latin "novem", "nine") or mensis November was originally the ninth of ten months on the Roman calendar, following October ("octo", "eight") and preceding December ("decem", "ten"). It had 29 days. In the reform that resulted in a 12-month year, November became the eleventh month, but retained its name, as did the other months from September through December. A day was added to November during the Julian calendar reform in the mid-40s BC. The outstanding event during November was the Plebeian Games from the 4th through the 17th. The month had few other festivals. It was
Adoption of the Gregorian calendar 12 days, only 11 were skipped, and the day of the week was repeated on successive days, because at the same time the International Date Line was moved, from following Alaska's eastern border with Canada to following its new western border, now with Russia. Many of the countries of eastern Europe were Eastern Orthodox or Islamic and adopted the Gregorian calendar much later than western Christian countries. Roman Catholic countries such as the Polish–Lithuanian Commonwealth adopted the "new style" (N.S.) Gregorian calendar in 1582 (switched back in 1795 after Third Partition of Poland), but the switch to the Gregorian calendar