I was reading this article about the first measures imposed under the state of emergency declared in France this morning and I kept coming across the word "couvre-feu." I hadn't seen this before and couldn't make sense of it because it basically means "cover-fire." After saying it out loud a few times, however, I had an inkling that it might be the root of our word "curfew."
And so it is. I guess it has its roots in the time when you would cover the hearth fire before going to sleep for the night.
Vachement chouette, non?