quarantine (n.)
Quarantine is a period of separation that keeps a disease from spreading. It comes from the Italian quaranta, forty.
During the plague, ships arriving from infected places could be kept at anchor for forty days before anyone came ashore. The Italian for forty is quaranta. The period became quarantena.
In 1920, ships carrying Russians who had fled the civil war were kept in quarantine off İstanbul before their passengers were allowed to land. Typhus was one of the main fears. Some later accounts say forty days, but contemporary memoirs and recent scholarship describe quarantines lasting from a few days to two weeks. I could not confirm forty days for the 1920 arrivals.12
A quarantine is rarely forty days now. It is ten days, or two weeks, or whatever the illness needs. The forty is still in the word.
The ship was held in quarantine.