Gregorian calendar, New Style calendar - the solar calendar now in general use, introduced by Gregory XIII in 1582 to correct an error in the Julian calendar by suppressing 10 days, making Oct 5 be called Oct 15, and providing that only centenary years divisible by 400 should be leap years; it was adopted by Great Britain and the American colonies in 1752

Columbus Day, Discovery Day, October 12 - a legal holiday commemorating the discovery of America by Christopher Columbus

October 24, United Nations Day - a day for celebrating the founding of the United Nations

Gregorian calendar month - a month in the Gregorian calendar

mid-October - the middle part of October

autumn, fall - the season when the leaves fall from the trees; "in the fall of 1973"