A fortnight is two weeks. Literally, fourteen nights. Why nights?
It seems that Germanic people called sunset the start of the day. The Anglo-Saxon people, should they have followed suit, would have naturally counted nights. And of course, we love counting here.
Half of a fortnight is seven nights, or a sennight. Sennite would be a natural name for a prequel game to Fortnite.
The fortnight as a unit of time
While looking into the etymology of fortnight, I ran across the humorous “microfortnight”, “millifortnight”, “nanofortnight”, and other units derived from metric prefixes added to “fortnight”. It appears these words exist primarily because of the Furlong-Firkin-Fortnight (FFF) system of units. How FFFunny! Now don’t get me wrong, I’m all in favor of questioning the merits of well-established status quo, including the SI system. But! I have an objection!
As far as I’m concerned, the fortnight doesn’t have a consistent duration. The entire reason the word fortnight exists is that a bunch of people used to measure their days from when the sun sets. Sunset time changes each day, so the exact amount of time from Sunset 0 to Sunset 14 is not fixed. And, for that matter, are we even 100% certain the fortnight is counted exclusively, and not inclusively?
So, even if we assume the time observer stays in the same place, a fortnight’s precise duration depends on the time of year! In fact, if we live at a latitude where the sun doesn’t rise at all for part of winter, a fortnight could be much longer than two weeks. It could be over six months long if we live at one of the poles.
But there’s a certain whimsy in having a system of units that changes based on where and when you are. It’s like an extreme version of how your mass stays the same, but your weight can ever-so-slightly vary throughout the planet, based on your local gravity. If I feel like it soon, maybe I’ll build an SI-to-FFF calculator that takes into account the changing sunset times.
Until that does exist, maybe stick with your current system of measurements.
