Why October is named for the number eight

October’s name preserves an older count

October comes from the Latin octo, meaning “eight.” In the traditional account of Rome’s early calendar, the year began in March and ran through ten named months, making October the eighth. January and February were later placed before March, shifting October to the tenth position without changing its name.

The other month names show the same shift

September, November, and December also retain number-based names: their Latin roots mean seven, nine, and ten. Once two months preceded them, they became the ninth, eleventh, and twelfth months instead. The mismatch is a small trace of how calendars accumulate changes: a new arrangement can alter the count while familiar names outlive the system that gave them meaning.

So October is not a mistaken name. It is an old piece of calendar arithmetic still visible in everyday speech.