You've likely memorized a half dozen mnemonics regarding the months of the calendar year — everything from remembering which months have 30 or 31 days ("Thirty days hath September …" or the knuckle mnemonic) to the order of months ("Just Follow My Amazing Memory Jogger! JASON Did!") to the Zodiac signs ("As The Great Cook Likes Very Little Salt, She Compensates Adding Pepper") and their symbols ("The Ramble Twins Crab Liverish; Scaly Scorpions Are Good Water Fish").
But how much do you know about how the names of the months came to be? Vague recollections of ancient Greek and Roman myths? Some Latin derivations? That's the right track: The months of the year are a vestige of an early Roman calendar, which is said to have been introduced by Romulus himself. Borrowing elements from the ancient Greeks, this calendar from the 8th century B.C.E. followed the lunar cycle and had 10 months in every year, with each month beginning with a new moon. (In fact, the English word "month" traces back to the word for "moon.")
During Roman times, the first day of these months was called a Kalend. (Derived from the ancient Greek word for "announce," this is where we get the English word "calendar.") The full moon was called the Ides and the first quarter moon was called the Nones. Dates weren’t numbered like our current system. Rather, they functioned as a "countdown" to and from these celestial events.
While today’s calendar now functions very differently, the name of each month still contains traces of the ancient past. Here’s a look.
March, or Martius, was named for the Roman god of war: Mars. It also marked the start of a new year, with Romans celebrating on the first new moon before the vernal (spring) equinox. The month’s name might have something to do with an early Roman tradition of avoiding warfare during the winter. With the arrival of spring, the war-fighting season had returned.
The origin of April’s name is one of history’s mysteries. Called Aprilis, it may derive from the Latin term aperire, meaning "to open" — a reference to the budding greenery of spring. But that explanation is uncertain. In fact, the month’s origin is so obscure that even the Romans themselves argued over what it might mean! The poet Ovid, for instance, suggested that it may be named after Aphrodite, the Greek goddess of love, pleasure, and procreation.
In the northern hemisphere, May is the season of flowers. So it’s probably unsurprising that May — or Maius — was named after the Greek goddess Maia, the guardian of nature and growing plants.
Today, June is a popular time for weddings. It appears that was always the case: The month — formerly called Junius — is named for the Roman deity Juno, the goddess of love and marriage.
Formerly the fifth month of the year, July was originally called Quintilis — literally meaning “fifth.” But in 46 B.C.E, Julius Caesar enlisted the help of mathematicians (and Cleopatra’s astronomer!) to reform the Roman calendar. At the time, the Roman calendar was 355 days long. Every few years, politicians inserted a new month, called Mercedonius, between February and March to make up for the growing gap. However, politics often got in the way. Mass confusion reigned, to the point where many Romans didn’t know what day it was. Caesar’s reforms addressed the problem, and in honor of this work, Quintilis (his birth month) was renamed Julius in his honor.
Originally the sixth month of the year, August was formerly called Sextilis. But it was renamed after Emperor Augustus Caesar demanded special treatment: Like his grand-uncle Julius, Augustus wanted a month for himself. Sometime around 27 B.C.E., the Roman Senate decreed:
“Whereas the emperor Augustus Caesar, in the month of Sextilis, was first admitted to the consulate, and thrice entered the city in triumph, and in the same month the legions, from the Janiculum, placed themselves under his auspices, and in the same month Egypt was brought under the authority of the Roman people, and in the same month an end was put to the civil wars; and whereas for these reasons the said month is, and has been, most fortunate to this empire, it is hereby decreed by the senate that the said month shall be called Augustus."
In Latin, the root of "September" — septem — means "seven," because it used to be the seventh month of the year. But other cultures have tried to spice up the name. In early Anglo-Saxon English, the period was reportedly called Gerstmonath, or "barley month." And in Switzerland, the month has been called Herbstmonat, meaning "autumn month."
Octopus. Octagon. Octet. Octave. Octuple. All of these words indicate a unit of eight. The same goes for October, which was the eighth month of the year during the heyday of the early Roman calendar.
Stemming from the root novem for "nine," November was the ninth month in the calendar of Romulus. In the 7th century C.E., Anglo-Saxon speakers supposedly referred to the month as Blōtmōnaþ, or "Blood Month," because, according to the scholar Bede, it was the "month of immolations" and a time for slaughtering cattle. Thankfully, the new name didn't stick.
Like its predecessors, December is a numbered month, with the Latin decem meaning "ten," for the tenth month. That said, some languages have tried on different names. During the French Revolution, France’s new government instituted an entirely novel calendar. Most of December was called Frimaire, derived from the word for "frost."
It's unusual seeing January near the bottom of the list. But, historically, this is where it belonged. In fact, back when the original Roman calendar was in use, the months of January and February didn’t even exist. Instead, winter was a monthless 70-ish-day period that stretched between December and March. That changed around 690 B.C.E. when King Numa Pompilius established Ianuarius, which is believed to be named for Janus, the two-faced Roman god of transitions and doorways. It's not certain when, exactly, January was moved to the top of the calendar; in some cases, Europeans were still treating March as the "New Year" into the 18th century.
Like January, Februarius was established to fill in the old monthless wintry period. Its name derives from the word februum, a reference to purification rituals. (Or to Februss, the god of purification.) Around the middle of the month, Romans celebrated a purification festival called, among other names, Februatus or Februatio. Whatever the exact origin, the month’s association with purification is apt. By February, Romans were busy purging their fields in preparation for spring planting. And with a new year around the corner, the time was ripe for a clean slate.