blue flag

noun4

1. •
   An award given to European beaches, based on cleanliness and water quality.
2. •
   A driver notification indicating a faster vehicle is coming up from behind.
3. •
   A driver notification indicating a faster vehicle that is ahead of the pilot's position in the race standings, is coming up from behind. An indicator that a lapping vehicle is coming up from behind, to lap the racer's vehicle.
4. •
   Ellipsis of command blue flag. A driver notification mandating the signaled vehicle move aside for a vehicle coming up from behind, to let it pass by.