Latin for 'eighth month' — a name meaning 'eight' stuck in tenth position since Rome expanded its calendar.
The tenth month of the year in the Gregorian and Julian calendars, consisting of 31 days.
From Latin 'Octōber,' derived from 'octō' (eight), because it was the eighth month in the original Roman calendar beginning in March. Like September, November, and December, its numerical name was never updated when January and February were added around 700 BCE, shifting it to tenth position. The emperor Domitian renamed it 'Domitianus,' and Commodus renamed it 'Invictus' (Unconquered), but both names were immediately revoked
Oktoberfest, the world's largest folk festival, actually begins in September and runs into the first weekend of October — the name refers to the month in which it originally ended, not when it mostly takes place. It was first held in 1810 to celebrate the marriage of Crown Prince Ludwig of Bavaria.