flag

A piece of cloth, often decorated with an emblem, used as a visual signal or symbol.

The design that could be placed on a flag, typically a rectangular graphic that is used to represent an entity (like a country, organisation or group of people) or an idea.

A flag flown by a ship to show the presence on board of the admiral; the admiral himself, or his flagship.

A signal flag.

The use of a flag, especially to indicate the start of a race or other event.

A variable or memory location that stores a Boolean true-or-false, yes-or-no value, typically either recording the fact that a certain event has occurred or requesting that a certain optional action take place.

In a command line interface, a command parameter requesting optional behavior or otherwise modifying the action of the command being invoked.

A mechanical indicator that pops up to draw the pilot's attention to a problem or malfunction.

The game of capture the flag.

A sequence of faces of a given polytope, one of each dimension up to that of the polytope (formally, though in practice not always explicitly, including the null face and the polytope itself), such that each face in the sequence is part of the next-higher dimension face.