Mysteries of vernacular: Quarantine - Jessica Oreck and Rachael Teel

Mysteries of vernacular: Quarantine, a state, period, or place of strict isolation meant to prevent the spread of disease.

In the 14th century, the Bubonic Plague, later called "The Black Death," spread across Europe with devastating consequences. It's been estimated that the Plague decimated at least one-third of Europe's population.

In a vain effort to stave off infection, the Italian-speaking port city of Ragusa, in what is now Croatia, mandated that ships arriving from Plague-infested areas remain isolated on the water until it was deemed likely that they weren't carrying a disease. This meant that the entire contents of a ship and all of its passengers were often forced to remain on board for five or six weeks before being let ashore.

Though the drastic measure was only marginally successful, it wasn't long before other port cities followed suit. In 1397, the official period of isolation imposed on ships and crews was set at forty days.

Although it did little to protect ports from infection, the directive stuck. From the Italian word quaranta, meaning forty, this period of stasis was given the name quarantine.

And by the mid 1600s, the word quarantine was being used to describe any place, period, or state of isolation, plague-related or not.