History of September: Where Did We Get That Name?

Bill Petro
2 min readSep 1, 2020

You may have noticed that September sounds like the Latin word for Seven. And you’d be perceptive — septem is the Latin word for seven, and this month used to be the seventh month of the ancient Roman calendar. This Latin numbering follows with the remaining months of the year, as I’ve highlighted below: eight/oct, nine/nov, ten/dec.


Legend has it that this calendar was started by Romulus, the founder and first king of Rome, at around 753 BC. The months counted up as follows:

  1. Martius — 31 Days
  2. Aprilis — 30 Days
  3. Maius — 31 Days
  4. Iunius — 30 Days
  5. Quintilis — 31 Days
  6. Sextilis — 30 Days
  7. September — 30 Days
  8. October — 31 Days
  9. November — 30 Days
  10. December — 30 Days

Doesn’t Add Up

This adds up to only 304 days, not enough to cover all four seasons without winter holidays. King Numa Pompilius reformed the calendar around 700 BC so that January and February were added to the beginning of the year.

Going Imperial

And I’ve written before, Quintiles was renamed July in honor of Julius Caesar in 44 BC, and Sextilis was renamed August in honor of Caesar Augustus in 8 BC. Emperor Commodus, son of Marcus Aurelius — made (in)famous by the movie Gladiator — tried to rename a month after himself, but this was repealed after his assassination in AD 192.

Changes to the Roman calendar could only be made by the pontifex maximus, the high priest of the College of Pontiffs in ancient Rome. When Julius Caesar became pontifex maximus, he reformed the calendar by getting rid of the intercalary months that had previously used to “pad” the calendar to fit the 365 days in a solar year.

Calendar Reform

The Julian Calendar reform began with Julius and was completed with Augustus. For a millennium and a half, the Julian Calendar was used, until Pope Gregory XIII introduced what became known as the Gregorian (or Western, or Christian) Calendar it in 1582. We use the Gregorian Calendar not only in the West but in other parts of the world to this day.

See you in September.

Bill Petro, your friendly neighborhood Roman

If you enjoyed this article, please consider leaving a comment, or subscribing to the news feed to have future articles delivered to your feed reader, or your email.

Bill Petro

Writer, technologist, historian. Former Silicon Valley tech exec. Author of fascinating articles on history, tech, pop culture, & travel. https://billpetro.com