- A flag is a piece of cloth, usually marked with a colourful symbol or sign.
- A flag flown by a ship is to show the presence on board of the admiral (the leader of a group of ships); the admiral himself; or his flagship.
- The use of a flag, especially to show the start of a race or other event.
- Be ready to start running immediately at the flag.
- On a computer, a flag is a variable or place in the computer's memory that keeps a true-or-false, yes-or-no value, usually either recording the fact that a certain event has happened or asking for a certain action to happen if it's an action that doesn't always happen.
- In a command line interface (a place on a computer screen for people to type commands for a computer to do), a sign telling the computer to do something it does only sometimes, or a sign changing in some other way the action of the command being typed.
- If you mark with a flag, it shows the importance of something.
- (often with down) To signal to, especially to stop a car that's driving past, etc.
- Please flag a taxi down for me.
- When a person flags, the person becomes weak, tired or feeble.
- His strength flagged toward the end of the race.
- To signal or mark something that happened.
- The compiler flagged three errors.
- To set the value of a variable in a computer program to true.
- Flag the debug option before running the program.