October is the tenth month of the year in the Julian and Gregorian Calendars and one of seven months with a length of 31 days. The eighth month in the old Roman calendar, October retained its name (from the Latin "octo" meaning "eight") after January and February were inserted into the calendar that had originally been created by the Romans. October is commonly associated with the season of autumn in the Northern hemisphere and spring in the Southern hemisphere, where it is the seasonal equivalent to April in the Northern hemisphere and vice versa. It is also very commonly associated with Halloween in western world. October's birthstones are pink tourmaline and opal. Its birth flower is the calendula. The Zodiac sign for October are Libra (until October 22) or Scorpio (October 23 onwards).