yellow jack

(redirected from Quarantine flag)
Also found in: Dictionary, Thesaurus, Wikipedia.

yellow jack

2. A yellow nautical flag formerly hoisted to warn of disease on board.
Mentioned in ?
References in periodicals archive ?
A yellow quarantine flag has to be flown as you enter the port and Customs must be notified of your arrival; contact the dockmaster at your chosen destination on VHF 16 for instructions.
We can talk of the good old days when life seemed simpler, but we often forget the quarantine flags draped on front doors of those critically ill.