Comprehensive resource for understanding and mastering English idioms
The idiom "zero hour" refers to a situation or time when an important event is about to happen, occur, or take place. It suggests that there is no more time left to do something before the moment of truth or judgment arrives. The figurative meaning is often used to describe a critical or decisive point in time.
The idiom "zero hour" has been used since the 19th century to describe a critical moment in time when something is about to happen or occur. It originated from military language where it referred to the hour when an attack could begin or be launched. The phrase gained popularity during World War II when air raids often took place at night and had to be coordinated precisely.