Curfew

Curfew \KUR-fyoo\ , noun;
1. An order establishing a specific time in the evening after which certain regulations apply, especially that no civilians or other specified group of unauthorized persons may be outdoors or that places of public assembly must be closed.
2. A regulation requiring a person to be home at a certain prescribed time, as imposed by a parent on a child
3. The time at which curfew starts and/or the period in which it is in effect

Curfew dates to the early 14th century as "evening signal, ringing of a bell at a fixed hour" from Anglo-French coeverfu, which derives from Old French cuevrefeu. Cuevrefeu is literally "cover fire" from couvrir + feu ("to cover" + "fire"). In Medieval times towns would have a rule about what time you had to put out your hearth and go to bed, the goal being to prevent fires. At the appointed time a bell would ring and everyone was supposed to cover the fire. The modern sense of "periodic restricted movement" evolved by the 1800's.