The word curfew has its roots in the Old French phrase "couvre-feu," meaning "cover fire." In medieval times, towns enforced fire safety by signaling residents to extinguish or cover their fires at a set evening hour, often marked by the ringing of a bell. This practice helped prevent devastating nighttime blazes in flammable wooden towns.

Over time, the term evolved from fire safety to mean enforced restrictions on movement during specific hours, especially in times of war or unrest. What began as a call to snuff out flames has become a symbol of order and caution through the ages.