quarantine flag

noun

Nautical.

1. a yellow flag, designating the letter Q in the International Code of Signals: flown by itself to signify that a ship has no disease on board and requests a pratique, or flown with another flag to signify that there is disease on board ship.

quarantine flag

noun

1. Also called: yellow flag.  yellow jack. nautical the yellow signal flag for the letter Q, flown alone from a vessel to indicate that there is no disease aboard and to request pratique or, with a second signal flag, to indicate that there is disease aboard

Word History and Origins

Origin of quarantine flag¹

First recorded in 1870–75

Example Sentences

Workers arriving in town must be quarantined for 14 days — either in a facility or on a ship, with a yellow-and-black quarantine flag raised.

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Quarantin′able, admitting of, or controlled by, quarantine.—Quarantine flag, a yellow flag displayed by a ship to signify the presence on board of contagious disease.

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It is advisable to fly a yellow quarantine flag as you enter the Bahamas until you�ve cleared customs.

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At her mizzen-peak flew the American ensign, and at the fore-truck the ominous quarantine flag.

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The yellow quarantine flag, hoisted to prevent communication; whence the term of the yellow flag, and yellow admirals.

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