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.