1. A period (originally 40 days) of detention of vessels and their passengers coming from an area where an infectious disease prevails.
2. To detain such vessels and their passengers until the incubation period of an infectious disease has passed.
3. A place where such vessels and their passengers are detained.
4. The isolation of a person with a known or possible contagious disease.
The definition information for quarantine is provided by Stedman's. You can search our medical dictionary here.