Flag
/flæɡ/
noun
A piece of cloth, often decorated with an emblem, used as a visual signal or symbol.
An exact representation of a flag (for example: a digital one used in websites).
A flag flown by a ship to show the presence on board of the admiral; the admiral himself, or his flagship.
verb
To furnish or deck out with flags.
To mark with a flag, especially to indicate the importance of something.
(often with down) To signal to, especially to stop a passing vehicle etc.
“Please flag down a taxi for me.”