In the ancient Roman calendar, Quintilis or Quinctilis was the month following Junius (June) and preceding Sextilis (August). Quintilis is Latin for "fifth": it was the fifth month (quintilis mensis) in the earliest calendar attributed to Romulus, which began with Martius ("Mars' month," March) and had 10 months. After the calendar reform that produced a 12-month year, Quintilis became the seventh month, but retained its name. In 45 BC, Julius Caesar instituted a new calendar (the Julian calendar) that corrected astronomical discrepancies in the old. After his death in 44 BC, the month of Quintilis, his birth month, was renamed Julius in his honor, hence July.

In the ancient Roman calendar, Quintilis or Quinctilis was the month following Junius (June) and preceding Sextilis (August). Quintilis is Latin for "fifth": it was the fifth month (quintilis mensis) in the earliest calendar attributed to Romulus, which began with Martius ("Mars' month," March) and had 10 months. After the calendar reform that produced a 12-month year, Quintilis became the seventh month, but retained its name. In 45 BC, Julius Caesar instituted a new calendar (the Julian calendar) that corrected astronomical discrepancies in the old. After his death in 44 BC, the month of Quintilis, his birth month, was renamed Julius in his honor, hence July.