The characters literally combine to mean “not aware of people or matters.” This creates a vivid and complete image of total unconsciousness—an inability to perceive the world or the people in it.
不省人事 is a formal chengyu (成语), a set idiomatic phrase. Its usage lends a sense of gravity and seriousness to a situation. In Western culture, we might use various terms depending on the context: “unconscious” (clinical), “knocked out” (from a blow), “passed out” (from fainting or alcohol), or “out cold.” 不省人事 covers the severe end of this spectrum and is closer to the clinical “unconscious.” While a friend might casually say, “He fainted,” (他晕倒了 tā yūn dǎo le), a news report or a doctor would more likely use the formal term 不省人事 to describe the same state. This reflects a common feature in Chinese where more formal, literary, or classical language is reserved for written communication, news, and serious situations. Using this chengyu immediately elevates the tone and signals the severity of the condition.
This term is frequently used in specific, serious contexts.
It is generally considered a neutral term in that it's a factual description, but the context it describes is almost always negative and serious.