- any geographical area that is thought to be dangerous or threatening, usually as a consequence of political or military activity.
- a level on a gauge or other measuring device that indicates danger. For example, air tanks contain a gauge that indicates when the pressure has reached a dangerous level.
- in American football, when a team gets the ball within twenty yards of the goal line, they are said to be in “the red zone,” since they have a higher likelihood of scoring.
- The alley behind the schoolyard is effectively a “red zone,” since that is where all of the bullies hang out.
- Something is wrong with my pressure washer; the gauge indicates that it is operating within the red zone.
- Although they were able to get into the red zone, the team failed to score a touchdown.
This idiom chiefly originates from scientific and regulatory documents, as well as military and diplomatic directives.
In a scientific article published in 1905, Charles H. La Wall used the term “rose-red zone” to describe a range of results that could be achieved when applying formaldehyde vapor to a solution of sulfuric acid and morphine sulphate (Proceedings of the Annual Meeting of the New Jersey Pharmaceutical Association, Volume 35, p. 72).
The Franco-British Treaty of 1916 delineated a variety of different zones within contested Middle Eastern territories, each of which was designated using a color term (blue, red, and brown). The red zone was established as a territory within which Great Britain would have authority, whereas the blue zone was under the administration of the French.
In the 1937 Federal Register of the United States, the Department of Commerce issued regulations governing civilian air flight. A section of the code stated:
“An aircraft flying along a red airway and continuing flight through a red zone of intersection shall… maintain an altitude approved for flight…”
The application of the term in the context of American football is often credited to Joe Gibbs, a former coach of the Washington Redskins, who adapted its military and geopolitical meaning as a metaphor for the 20 yards in advance of each goal line.