October is the tenth month of the year in the Julian and Gregorian calendars and the sixth of seven months to have 31 days. The eighth month in the old calendar of Romulus c. 750 BC, October retained its name (from the Latin and Greek ôctō meaning "eight") after January and February were inserted into the calendar that the Romans had created. October is commonly associated with spring in parts of the Southern Hemisphere and autumn in parts of the Northern Hemisphere. It is the seasonal equivalent to April in the Southern 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.