To the Four: Dissecting the bissextile year

Why is it called bissextus? The word has origins in the Latin bis (twice) and sextus (sixth). It was so called because February 24, the sixth day before the calends (first) of March appeared twice every leap year.

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When I opened my mail after a week-long holiday recently, a greeting dated February 29 caught my attention: "Happy Bissextus Day!" It sounded kind of naughty. But reference to the dictionary showed that the word bissextus does not allude to any sexual orientation. It refers to February 29, the extra day added to the Julian calendar every fourth year (except those evenly divisible by 100, unless they are divisible by 400) to compensate for the approximately six hours a year by which the common year of 365 days falls short of the solar year. 

The solar year is not evenly divisible by 365. The Earth makes a complete revolution around the Sun is 365 days, 5 hours, 48 minutes, and 46 seconds. If we didn't account for that remainder, Christmas would one day fall in the summer.

In today's common parlance, it is the leap day in the leap year. If we go by the hashtags that bissextus got on the social media this year, this ancient word has taken the leap from obscurity to popularity. Even though both the old Roman lunar calendar and Julian calendar have, by and large, been discarded.

But why is it called bissextus? The word has origins in the Latin bis (twice) and sextus (sixth). It was so called because February 24, the sixth day before the calends (first) of March appeared twice every leap year. The name describes exactly what it is: the double "sixth" day before the beginning of March, ie February 24th.

Originally, the odd day was inserted after February 24. It was not counted as an addition to the year, but as a kind of appendix. Incidentally, in ancient Roman times, the New Year began on March 1. That also explains the nomenclature of September (as the name implies, seventh month), October (eighth), November (ninth) and December (tenth month). And yes, calendar comes from calend.

And, there was a practice to count days backwards from the calends (the first of a month). Thus, besides the sextus, or sixth before the calends, the bis-sextus or "second sixth" was the 25th of February, the original leap day. In modern times, the intercalary day is added at the end of February, as February 29. The year in which February has 29 days is called the bissextile year or leap year.

It was only when Julius Caesar reformed the Roman calendar by introducing the Julian Calendar in 46 BC that the seasons were lined up with the standard year length of 365 days. In fact, Caesar had to lengthen the year 46 BC to 445 days to achieve this. This year is also known as the "Year of Confusion". His astronomers calculated that an extra day every four years would keep the time and days correctly matched. This was gradually replaced by the more precise Gregorian calendar, promulgated in 1582 by Pope Gregory XIII. The modern system of counting days forward from the beginning of the month took over and the leap day was gradually moved from February 25 to February 29. 

Before Caesar, Rome used a flawed lunar calendar. In that old Roman system, the months were divided into day markers called calends (the first of the month, coinciding with the new moon), nones (the fifth or seventh day), and ides (the middle of the month). Individual days were referred to by how many days they fell before the calends (the first day of a month), nones (seventh day), and ides (the fifteenth day). The other days were called in reference to these days, eg bissextus was the sixth day before the March calends.

In this context, the OED definition of bissextus becomes clear: "the name given to the intercalary day inserted by the Julian calendar every fourth year after the sixth day before the calends of March."

This reminds me of a friend whose birthday I can never forget because she told me: "Thank God, I was born on February 28. One day later, and I would have had to wait for four years to celebrate my birthday!" But on the flip side, leap day people stay younger since their birthday comes once in four years!

By the way, if you have a French friend, he might consider the day as unlucky. TF Thiselton Dyer in "Antiquarian Gossip on the Months" says: "The Romans looked upon the bissextile, or leap day, as unfortunate, and in the Middle Ages this superstition was extended to the whole year. The French are still in the habit of saying, when any misfortune happens, that the bissextus has fallen upon the business."

While we are in the bissextile year, let me tell you of an interesting tradition. It is said that in the olden times, girls were allowed to propose marriage to men only in the leap year and then, the men could not decline the proposal. So, what are you waiting for? Take the leap!

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