1. an automatic device for stopping the flow of current in an electric circuit as a safety measure.
▪ a short period in which travel, business, and human contact are restricted in order to prevent the spread of an infectious disease: "a circuit breaker was recommended by the government's official scientific advisers"
▪ a temporary halt automatically placed on trading as a means of inhibiting panic selling:"the circuit breaker was triggered as plunges reached 7 per cent"