The word 事故 is formed by combining two characters: 事 (shì), which means "event" or "matter", and 故 (gù), which in this context carries the meaning of "reason", "cause", or "unintended occurrence". Together, they conceptually create the idea of "an event caused by an unforeseen reason", visually and semantically painting a picture of an incident that is not a simple happening, but one with an underlying, often negative, cause or unexpected origin, hence converging to mean "accident" or "mishap".