October is the tenth month of the year in the Julian and Gregorian calendars and the sixth of seven months to have a length of 31 days. The eighth month in the old calendar of Romulus 750 BC, October retained its name (from Latin and Greek ôctō meaning "eight") after January and February were inserted into the calendar that had originally been created by the Romans. In Ancient Rome, one of three Mundus patet would take place on October 5, Meditrinalia October 11, Augustalia on October 12, October Horse on October 15, and Armilustrium on October 19. These dates do not correspond to the modern Gregorian calendar. Among the Anglo-Saxons, it was known as Winterfylleth (Ƿinterfylleþ), because at this full moon, winter was supposed to begin.
October is commonly associated with the season of spring in parts of the Southern Hemisphere, and autumn in parts of the Northern Hemisphere, where it is the seasonal equivalent to April in the Southern Hemisphere and vice versa.
October's birthstones are the tourmaline and opal. Its birth flower is the calendula. The zodiac signs are Libra (until October 22) and Scorpio (from October 23 onward).
The French word octobre is shortened to 8bre.
This list does not necessarily imply either official status or general observance.
(All Baha'i, Islamic, and Jewish observances begin at the sundown prior to the date listed, and end at sundown of the date in question unless otherwise noted.)
List of observances set by the Bahá'í calendar
List of observances set by the Chinese calendar
List of observances set by the Hebrew calendar
List of observances set by the Islamic calendar
List of observances set by the Solar Hijri calendar
Black History Month in the United Kingdom
In Catholic Church tradition, October is the Month of the Holy Rosary.
Breast Cancer Awareness Month
Health Literacy Month
International Walk to School Month
Medical Ultrasound Awareness Month
Rett Syndrome Awareness Month
World Blindness Awareness Month
World Menopause Month
Vegetarian Awareness Month
The last two to three weeks in October (and, occasionally, the first week of November) are normally the only time of the year during which all of the "Big Four" major professional sports leagues in the U.