yellow flag

n. quarantine flag, yellow flag flown by itself by a ship requesting pratique on entering a harbor to indicate that the ship has no disease on board; flag flown by a ship with another flag to indicate that it has contagious or infectious disease aboard; yellow flag raised by a ship that has been quarantined (Shipping); yellow iris (Botany); solid yellow flag used to indicate caution due to dangerous conditions (Car Racing)

This article is about the yellow flag iris. For the penalty flags in American football, see American football#Penalties. For the yellow flag used in auto racing, see Racing flags. Iris pseudacorus is a species of Iris, native to Europe, western Asia and northwest Africa. Common names include yellow iris and yellow flag. Its specific epithet, meaning "false acorus," refers to the similarity of its leaves to those of Acorus calamus, as they have a prominently veined mid-rib and sword-like shape.
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Noun
1. common yellow-flowered iris of Europe and North Africa, naturalized in United States and often cultivated
(synonym) yellow iris, yellow water flag, Iris pseudacorus
(hypernym) iris, flag, fleur-de-lis, sword lily