The Welsh for October is Hydref (originally Hyddfref), a word signifying the lowing of cattle. The Anglo-Saxons, however, called October Winterfylleth (or Winterfilth as Tolkien's hobbits preferred it) meaning the 'fullness' (rather than 'dirtiness') of winter.
According to a recent study in Italy, October is the best month for conceiving a boy. This would not have applied in Catholic Europe in 1582, when October had only 21 days. Because of the change to the Gregorian calendar, the days from 5 to 14 October were omitted.
The 'October Revolution' in Russia in 1917 took place in November, but at the time Russians had not yet changed from the Julian calendar. Even when its anniversary had moved into November, they continued celebrating the October Revolution.