blue flag(redirected from Poison Flag)
Also found in: Thesaurus, Medical.
Any of several irises having blue or blue-violet flowers, especially Iris versicolor of eastern North America.
(Environmental Science) an award given to a seaside resort that meets EU standards of cleanliness of beaches and purity of water in bathing areas
any of several North American irises having blue flowers.
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|Noun||1.||blue flag - a common iris of the eastern United States having blue or blue-violet flowers; root formerly used medicinally|