Definition of yellow flag in US English:

yellow flag


  • 1A ship's yellow flag, denoting the letter Q for ‘quarantine.’ When flown with another flag, it indicates disease on board; when flown alone, it indicates the absence of disease and signifies a request for customs clearance.

    Also called quarantine flag
    • ‘A hatch opened on the top of the ship, revealing a Mulinyan admiral, carrying the red and yellow flag and a voice amplifier.’
    • ‘Placards or yellow flags traditionally marked places under quarantine.’
    1. 1.1Motorsports A yellow flag used to signal to drivers that there is a hazard such as oil or a crashed car on the track.
      • ‘But it was nice to be reminded what a checkered flag was, what a [last-lap] white flag was, and no black flags, no yellow flags.’
      • ‘We had some help with the yellow flags during the race and I was able to get close enough to put a pass on Terry Borcheller on the last lap.’
      • ‘My only problem was that I had yellow flags on my two laps on new tyres so I wasn't able to make use of them.’
      • ‘For this reason use of the safety car should be kept to a minimum, replaced by outright race stoppages or use of double-waved yellow flags.’
      • ‘Retirements included Ryan Hunter Reay who crashed heavily on the sixth lap bringing out the yellow flags.’
  • 2A yellow-flowered iris that grows by water and in marshy places, native to Europe and naturalized in North America.

    Iris pseudacorus, family Iridaceae

    • ‘We spotted two clumps of yellow flag or yellow iris growing along the edge of Sleepy Hollow Lake with other wild flowers.’
    • ‘Once balance is restored, then well-protected shallow margins will be easier to colonise with wetland wildflowers such as flowering rush, yellow flag, marsh marigold and water forget-me-not.’
    • ‘Here the river is fabulous, clear and convoluted, with ponds jammed with yellow flag irises where there are springs or oxbows.’
    • ‘Arram Beck cuts in, straight, canalised and with water crowfoot and flowering yellow flag iris.’
    • ‘Rooted into this the plants, such as reeds, water lilies, flowering rushes, Cyperus longus and yellow flag irises, do their job of taking nitrates out of the water and reducing phosphates.’


yellow flag

/ˌyelō ˈflaɡ//ˌjɛloʊ ˈflæɡ/