Comprehensive resource for understanding and mastering English idioms
The idiom "red zone" refers to a high-risk or dangerous area. It can be used to describe a physical location, such as a war-torn region or an area with high crime rates, or a metaphorical location, such as a person's temperament or a situation that poses a risk.
The idiom "red zone" has been used since at least the 19th century. It may have originated from the practice of marking off areas in a warzone as "red zones," indicating that they were under fire or had high mortality rates. Over time, the idiom has been applied to other situations that pose a risk, such as physical danger, emotional turmoil, and financial instability.