Comprehensive resource for understanding and mastering English idioms
The idiom "black out" means to lose consciousness or to become unconscious due to lack of oxygen, injury, illness, or other reasons. It can also refer to a power outage that causes the lights and other electrical devices to go off. In metaphorical terms, it can mean to forget something important or to be overwhelmed by a situation.
The idiom "black out" has been used since at least the 19th century. It originally referred to a complete loss of consciousness or memory. However, over time, it has taken on several other meanings, including being overwhelmed by a situation or forgetting something important. In modern times, it is also commonly used to refer to a power outage that causes the lights and other electrical devices to go off.