“Quarantine” Originally Meant Exactly 40 Days
Today, a quarantine can last five days, ten days, or several months. But the word originally referred to one precise period: forty days.
It comes through French from the Italian quarantena, derived from quaranta, meaning “forty.” During the plague outbreaks of the Middle Ages, Mediterranean port cities feared that arriving ships might carry deadly disease.
Venice initially required suspicious vessels to remain isolated for thirty days—a period called a trentino, from the Italian word for thirty. Authorities later extended the waiting period to forty days, which became known as a quarantena.
Why forty? The exact reason is uncertain. It may have seemed medically safer, but forty also carried powerful religious meaning: the biblical flood lasted forty days, Moses spent forty days on Mount Sinai, and Jesus fasted for forty days.
Over time, quarantine stopped meaning strictly forty days and came to describe any enforced separation intended to prevent disease from spreading. Its meaning expanded again in the digital age: suspicious computer files can now be “quarantined” to stop them from infecting a system.
So whether isolating a medieval ship or a modern computer virus, quarantine still carries the memory of forty anxious days at sea.
