quarantine flag
noun
: a yellow flag hoisted by all ships to request pratique on entering a harbor, by a ship to show that it has contagious or infectious disease aboard, or by a ship that has been quarantined
called also yellow flag, yellow jack
Cite this Entry
“Quarantine flag.” Merriam-Webster.com Medical Dictionary, Merriam-Webster, https://www.merriam-webster.com/medical/quarantine%20flag. Accessed 4 Nov. 2025.
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