November is the eleventh month of the year in the Julian and Gregorian Calendars, the fourth and last of four months to have a length of 30 days, and the fifth and last of five months to have fewer than 31 days. November was the ninth month of the calendar of Romulus c. 750 BC. November retained its name (from the Latin novem meaning "nine") when January and February were added to the Roman calendar. November is a month of late spring in the Southern Hemisphere and late autumn in the Northern Hemisphere. Therefore, November in the Southern Hemisphere is the seasonal equivalent of May in the Northern Hemisphere and vice versa.
A month is a unit of time used with calendars, which is approximately as long as a natural period related to the motion of the Moon; month and Moon are cognates. The traditional concept arose with the cycle of moon phases; such months (lunations) are synodic months and last approximately 29.53 days. Researchers have deduced that people counted days in relation to the Moon's phases from excavated tally sticks as early as the Paleolithic age.