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How Did The Months Of The Year Get Their Names?

From January to December, these names raise our curiosity. How did the months of the year get their names? We can trace the origins of calendars to ancient Rome and Egypt. Currently, we are using one that has evolved from the old Roman calendar. So, the names of the months are the names of Roman gods. 

Here, you’ll read about the evolution of calendars. You will learn about the reforms of various Roman emperors and ‌the origin of the month's names. 

Related Read: How Did The Days Of The Week Get Their Names?

Evolution of Calendars 

paper calendar
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The current calendar we use, the Gregorian calendar, is from the ancient Roman and Julian calendars. In this section, we'll discuss the brief history of the major calendars in the world. These calendars are:

Related read: Grab an eco-friendly planner or diary to help you plot the next year ahead.

Early Roman Calendar 

The Roman Empire used the early Roman calendar, and the Roman rulers and emperors put it in place. Initially, they based the Roman calendar on moon cycles and agricultural seasons4. This calendar had ten months, which started in March and ended in December.

They couldn't account for the winter periods because there were no winter months. The new year has always started on the first day of spring, a few days before the 15th of March. The total days of the months of the year were 304, with four months having 31 days and six months having 30 days.  

History shows that the second king of ancient Rome, Numa Pompilius, changed the Roman calendar. He divided the year into twelve lunar months and added more days to account for the missing winter days between the years. He added 50 days to the calendar and removed two days out of every month with 30 days. Each removed day, besides the 50 added days, created the months Januarius and Februarius.

The Roman emperor's addition made the number of days 354. However, he added one day to January because of the Roman superstition about even numbers. They believed even numbers were unlucky numbers. So, the total number of days in the Roman calendar is 355. January, March, May, Quinctilis, and October have 31 days, while the days in February vary between 28,24 and 23 depending on when they introduce the intercalary month.

During some years, they added some days to account for some seasons. These days make up the intercalary months. The extra days were usually in the second half of February. The months of the year had an average of 366 days. These intercalary months were primarily subject to the political season.

Julian Calendar 

They named the Julian calendar after Julius Caesar and introduced new reforms to the ancient Roman calendars3. Julius Caesar changed the old Roman calendar to a solar calendar, as it aligned more with the solar cycle. The previous calendar has an intercalary month between February and March, lasting 27-28 days. 

The Roman politicians often misused these intercalary months for their benefit. Since their political office term aligns with the calendar year, they often lengthened the year to suit their greed for power. Julius Caesar's reform set to align the calendar with the solar cycle without constant human intervention. 

Speculations suggest he got the inspiration for the reformation during his travels in other lands, i.e., Persia and Egypt. He returned and ordered the reconstruction of the Roman calendar. The best philosophers and mathematicians joined to create the calendar named after Julius Caesar. 

They didn't change the long months and February in the Julian calendar. Instead, they added ten more days to the short months. The extra addition totaled the days of the year to 365 days. In the fourth year, there were 366 days because of the leap day in February. 

So, the days of the month were 30 or 31. February is the only short month with 28-29 days. Later, the pontiffs were renamed some months to honor Julius Caesar and Augustus Caesar. He changed the month of Quintilis to July to honor Julius Caesar's birth and death and Sextilis to Augustus to celebrate his achievements in the Roman Empire.

Gregorian Calendar 

Pope Gregory XIII introduced new reforms to the Julian calendar in 1582. He gathered the best astronomers, mathematicians, and clergymen to fix the error in the old calendar. The Gregorian Calendar accounted for the overestimation in the Julian calendar that led to a day's increase every 128 years. 

This error meant the dates coinciding with astronomical events kept moving farther away from the actual occurrence. The Gregorian calendar is the shortened version of the Julian calendar. Pope Gregory XIII shortened it by 0.0075 days. 

The Catholic Church pushed for reforming the old calendar because they had difficulty determining the dates for church events. For instance, they needed the spring equinox to set the date for Easter Sunday. Spring Equinox was supposed to happen on the 21st of March, but it was happening days earlier. 

He removed ten days from the calendar to balance it up. Also, the previous calendar had too many leap years. The Gregorian calendar fixed it by removing centenary years as leap years. Centenary years can only become a leap year if divisible by 400. 

The calendar slowly became the universal calendar in the world. Italy, France, Spain, and Portugal adopted the calendar in 1582, while the Netherlands, Denmark, and Sweden adopted it in 1700. Great Britain, America, Japan, and China adopted the Gregorian calendar in 1752, 1872, and 1912, respectively. 

Other countries that later adopted the Gregorian calendar were Greece, Bulgaria, Turkey, Romania, and Russia. We still use this calendar in most parts of the world today, during the 21st century.

How did the months of the year get their names?  

Today’s Gregorian calendar still uses the same names as the months of the ancient Roman calendar despite the reformations that occurred1. The name of each month of the year is tied to a Roman god or a Roman emperor. 


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In the early Roman Calendar, January wasn't the first month of the year. In fact, January was non-existent until Roman Emperor Numa added it to the old 10-month structure. Then, Januarius replaced Martius in the first month of the year. 

The people named the month after the Roman god Janus. The Roman god Janus represents the Roman god of beginnings. They also called him the protector of pathways, doors, and gates. The name Januarius is of Latin origin: janu + arius, with arius translating to about. 

They usually referred to January as Januarius mensis, meaning the month of Janus. During this month, Romans usually celebrate the Roman god Janus. January used to have 29 days until Julius Caesar changed it to 31 days.

Related Read: January Quotes.


Roman people commonly referred to the second month of the year as mensis februarius. February used to be the last month of the year. It is the month of the Roman purification festival. February was from the Latin word februa, the name of a purification instrument in ancient Rome. 

The februa was a purification tool used in the Roman purification festival. It was the Lupercalia festival. The festival's purpose was to purify the bad omens present in the cities at the end of their calendar year.

Related Read: February Quotes.


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The origin of the name of the third month of the year, Martius, was from Latin. It translates to Mars. Roman Emperor Romulus named the month after the Roman god of war, Mars. Mars was also recognized as the protector of Roman agriculture and government. March has always been 31 days since the early days of the Roman calendar.

As March used to be the first month of the year, they celebrate the Roman god of war and the state of the Roman government. Old English called it Martius, but it changed to March because the Anglo-French and Middle English people started calling it March(e).

Related Read: March Quotes.


The fourth month of the year has no traceable origins. Even the Romans were uncertain about the etymology of the word. There's the school of thought that believes April is from the Latin word aperio, aperire, or Aprilia. 

The Latin word aperio means to open. It does make sense because it's a month with warm weather, blossoming flowers, and overall agricultural prosperity. April was the Roman period of several agricultural festivals. It was the opening springtime month. 

Some people also think that April has some ties to Greek and Roman deities. It could be linked to the Greek goddess of love and beauty, Aphrodite. Romans usually celebrate the Roman goddess of love, fertility, and beauty, Venus, in April.

Related Read: April Quotes.


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May, the fifth month of the year, is the month of early harvest. The crops planted during springtime are growing, and the fruits are ready for harvesting. 

Romans commemorated this important period by naming the month after the Roman goddess Maia, the goddess of spring. She is not to be confused with the Greek goddess Maia, who is the mother of Hermes.

Roman goddess Maia is an earth goddess and goddess of growth. She represented healthy soils and successful harvests. The old English people called the month Maius, while the old French called it Mai.

Related Read: May Quotes.


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The month of June got its name from the Roman goddess Juno. The Roman goddess Juno is the patroness of marriage and the well-being of young people. The Latin word Junius also means youth. 

Related Read: June Quotes.


July was originally called Quintilis, the fifth month. Speculations have it that the Romans were tired of thinking up cool names for the months of the year. Julius Caesar, however, changed two things about the Quintilis month. He changed its placement in the calendar year by adding two extra months. 

Also, his lifetime achievements inspired the Romans to change the fifth month to Julius. It was a way to keep his legacy on. However, we have shortened the name of the month to July. 

Related Read: July Quotes.


The month of August was formerly known as the sixth month, but the Romans renamed it to honor Julius Caesar's heir. Augustus Caesar was the first emperor of the new Roman Empire. He was a successful Roman ruler who won wars, stopped the civil war, and subdued nations. 

He was also the one who implemented Julius Caesar's calendar in its early years. A few years after he died in 14 BC, the Roman Senate renamed the month Sextilis to Augustus. Now, we've shortened it to August. August used to be 30 days before King Numa changed it to 29. However, it's been 31 days since Julius' reform. 

Related Read: August Quotes.

September/Seventh Month

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September comes from the Latin word septem, the seventh month of the year. As you can already tell, Romans lost the flare of naming months when it got to the fifth month, now known as July. They called the months according to their numerical position on the Roman calendar. 

Related Read: September Quotes.

October/Eighth Month

Like September, October is the Latin word for eight. October means it's the eighth month of the year. 

Related Read: October Quotes.

November/Ninth Month

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November is from the Latin word novem, meaning nine. Just like other 'ember' months, November means the ninth month. 

Related Read: November Quotes.

December/Tenth Month 

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The last month in the Roman calendar is December. December is from the Latin word decem, meaning the ten. December translates to the tenth month of the year. 

Related Read: December Quotes.

Other Types of Calendars from Around the World 

There are other types of calendars apart from the Roman calendar that evolved to be the universal calendar of the world. These calendars are the Egyptian calendar, Hindu calendar, and Jewish calendar. 

Egyptian Calendar 

The calendar of ancient Egyptians was one of the earliest experiments in creating calendars. Ancient Egypt used three types of calendars. They used a lunar calendar, an administrative calendar, and the lunar-civil calendar. The first calendar was a lunar calendar based on the moon's movements. It had 12 months and a leap month. They mostly used the lunar calendar for religious festivals. 

The second calendar was for governance and administrative reasons. The administrative calendar had 365 days split into 12 solar months, and each month had 30 days, with an extra five days added to the end of the year. 

However, they regarded these five days as unlucky days. Egyptians used the third calendar to determine the civil years. They used the lunar cycle to match with the civil year2. They based this calendar on 25 civil years, which had 305 civil months.

Conclusion: How Did The Months Of The Year Get Their Names?

The universal calendar we use is from the ancient Roman calendar. Julius Caesar reformed the calendar by adding two extra months. It became a 365-day calendar. The church reformed the Julian calendar after thousands of years. Pope Gregory XIII removed ten days from the calendar, and the fourth year was a leap year. 

Despite these changes, the names of the month remained the same. The Romans named the first five months after the Roman god, and they named the rest based on their numerical positions using a base Latin word for numbers. These months are September, October, November, and December. They only renamed July and August.


Thakar, P. (2020). A History of the Months and the Meanings of Their Names. ResearchGate. 


Depuydt, L. (2017). The Calendars and the Year-counts of Ancient Egypt. Chronique d’Egypte. 


 Hall, M. L. (n.d.). 12.1.8 Julian_Day Procedure. 


Rüpke, J. (2015). Calendar, Roman. Oxford Research Encyclopedia of Classics. 

Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.

Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.

Fact Checked By:
Isabela Sedano, BEng.

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