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.
December begins (astrologically) with the sun in the sign of Sagittarius and ends in the sign of Capricorn. Astronomically speaking, the sun begins in the constellation of Ophiuchus, which is the only zodiacal constellation that is not counted as an astrological sign, and ends in the constellation of Sagittarius.
The name is from the Latin decem for "ten". December was the tenth month in the Roman calendar until a monthless winter period (summer in the southern hemisphere) was divided between January and February.
In old Japanese calendar, the month is called Shiwasu (師走).