Which is an order specifying a time during which certain regulations apply?

A curfew is an order specifying a time during which certain regulations apply. Typically it refers to the time when individuals are required to return to and stay in their homes. Such an order may be issued by public authorities but also by the head of a household to those living in the household. For instance, an au pair is typically given a curfew, which regulates when they must return to the host family's home in the evening.

The word "curfew" comes from the French phrase "couvre-feu", which means "cover fire".

It was later adopted into Middle English as "curfeu", which later became the modern "curfew". Its original meaning refers to a law made by William The Conqueror that all lights and fires should be covered at the ringing of an eight o'clock bell to prevent the spread of destructive fire within communities in timber buildings.