December is the twelfth and last month of the year in the Gregorian Calendar and one of seven Gregorian months with the length of 31 days. In Latin, decem means ten. December was also the tenth month in the Roman calendar until a monthless winter period was divided between January and February. December's flower is the narcissus or holly. December's birthstones are turquoise, lapis lazuli, zircon, topaz (blue), or tanzanite. December is the month with the shortest daylight hours of the year in the Northern Hemisphere and the longest daylight hours of the year in the Southern Hemisphere. December starts on the same day of the week as September.