During the life of Gaius Marius Insubrecus, the traditional twelve months of the Roman year based on Caesar’s reform of the calendar were named
Quintilis, the birth month of Gaius Iulius Caesar, was renamed Iulius in his honor in 44 BCE, the year of his death. To honor Augustus, Sextilis was renamed Augustus in 8 BCE.
Those of you who are familiar with Latin, or the Romance languages, may have noticed an incongruity in the names of the Roman months. For example, why is the twelfth month of the year called 10, December.
The calendar of Romulus, Rome’s mythical founder, originally began 1 March and had only ten months.
Six of the months were named with respect to their position on the calendar: 5, quinque; 6, sex; 7, septem; 8, octo; 9, novem; and 10, decem.
Martius seems to have been named after Mars, the god of war, since March was the beginning of the campaign season. Aprilis seems related to apricus, which indicates the month warm under the sun. Maius seems either derived from the goddess, Maia, goddess of growth, or from maiores, the ancestors.
Ovid presents three possible derivations for Iunius. The goddess, Iuno, claims that the month is named for her. Iuventas, the goddess of youth, claims the month for herself. Finally, Ovid claims that Iunius comes from the verb, iungere, “to join”, to mark the alliance between the Romans and the Sabines.
The months Ianuarius and Februarius were appended to the end of the Roman year in a calendar reform attributed to Numa Pompilius, the second of the seven traditional kings of Rome.
Ianuarius seems to have been named after the god, Ianus, the god of transitions, as the winter solstice signals the transition from winter to spring. Ancient sources derived Februarius from Februus, another name for the god, Lupercus, who has to do with expiation and ritual purification and whose festival is celebrated around the Ides of Februarius.