It’s bissextile …

Monday afternoon, I realized something fairly mundane but nonetheless rare: it was Leap Year and today was going to be Leap Day. Sitting at my desk, I turned to Michel and I started to tell him that (in French, because we almost always speak in French now), but I stopped short when I couldn’t find the word …

“Hé, Michel. Mercredi, on sera le jour de … euh … c’est le …
tu sais … le 29 février. Comment on dit ça en français?”
“Hey, Michel. Wednesday is the day of … um … it’s the …
you know … the 29th of February. How do you say that in French?”

“Oh, c’est la bissextile.”
“Oh, it’s the bissextile.”

<one raised eyebrow>

“Euh, la quoi?”
“Uh, the what?”

After my brain had a few seconds to parce the word and realize it had nothing to do with what I thought I’d heard, I started to wonder how the French came up with the name. It didn’t seem to have anything at all to do with leaping, or jumping, or hopping …

As usual, I did a little low-level research (meaning lots of Wikipedia articles). Michel was actually using the French adjective describing Leap Year. The adjective bissextile and the far less common noun for Leap Day, bissexte, come from the Latin word for the extra day in a Leap Year : bisextus, which itself is formed from bis (twice, second) plus sextus (the sixth). Okay, but why bisextus … why “the second sixth”?

To make a very long, quite complicated story a little shorter and hopefully more straightforward :

It was Julius Caesar who introduced the concept of the Leap Day to the Western World. Before Caesar, the Roman year was 355 days long, with 12 lunar months (very similar to the Jewish and Islamic calendars). Every so often, in order to bring the calendar back into alignment with the solar calendar, an extra month of 27 days was inserted (similar to the Jewish intercalary month of Adar I). Generally speaking, this would recalibrate things so that the seasons made sense again. Unfortunately for the Romans, though, there was no hard, fast rule for how often this extra month was inserted into the calendar, so the seasons were still often out of whack. Inserting an extra month was a political decision and—true to form—politicians often manipulated the decision to serve their own interests (since political terms were based on the calendar year).

The Julian reforms did away with all of this and instituted a more streamlined system. The first step was to add almost 100 days to the year 46 B.C., to realign the calendar with the solar year. Then, some of the months were lengthened to give the year 365 days. Finally, the Leap Day was inserted once every few years to recalibrate for the extra almost six hours not accounted for each calendar year. The interesting thing about the first Leap Day, however, is that it wasn’t inserted after February 28 (as it is today) but after February 23 …

The reason for this is a throwback to that old Roman calendar. Remember the extra month that was added from time to time? When they got around to doing it, the Romans added that extra month right after the 23rd day of February, because that was the end of the Roman religious year. (The last five days of February ended up being “absorbed” by the extra month.) In keeping with that tradition, the new Julian Leap Day was added to February at the same point, so the first one actually came the day after February 23.

Now, stay with me here, because here’s where the name “bisextus” comes from. Pay close attention :

The Romans weren’t that fond of counting sequentially. (Just think about how to write “4” or “9” in Roman numerals.) When it came to dates, they were just as backwards—literally. The Romans actually counted backwards from important days in the month, like “kalends” (the first day of the month) and “ides” (the middle of the month). They also counted the reference day as day 1 (instead of day 0) so, for example, April 25 was “VII Kal. Mai.” or the “Seventh day before the First of May.” Getting back to our story, then, February 24 was “VI Kal. Mart.” or the “Sixth day before the First of March.” After the Julian reforms, when Leap Year rolled around, the Romans inserted another day between February 23 and 24. We might call such a date February 23½, but the Romans called it “Bis VI Kal. Mart.” or the “Second sixth day before the First of March.” When we eventually started numbering the days of a month consecutively during the Middle Ages, Leap Day was moved to the last day of February in Leap Years—February 29—but the terms bissextile and bissexte stuck around.

So that’s the story of why 2012 is l’année bissextile and why February 29 is le bissexte (though no one really says that these days). It’s a convoluted story, but it makes sense once you understand how messed up the Roman calendar was. Come to think of it, the better question isn’t why the French say bissextile and bissexte, but why we say “Leap Year” and “Leap Day.”

<one raised eyebrow>

P.S.—A note on bis :

The Latin word bis makes an appearance in English, especially in musical scores, where it is used to indicate that a passage is to be repeated. In French, bis also denotes something that occurs twice and is frequently used in street addresses. For example, whereas in English you might see something like “120½ Green Street” for the address between 120 and 121 Green Street, in French you would see something like “23 bis rue Hugo” for the address between 23 and 24 rue Hugo.

P.P.S.—A note on “bissextile” :

Although we don’t use “bissexte” in English, the adjective “bissextile” is used—though not commonly—to describe Leap Year.

© 2012 Samuel Michael Bell, all rights reserved