circuit breaker

American  

[sur-kit brey-ker] / ˈsɜr kɪt ˌbreɪ kər /

noun

1. Also called breaker.  Electricity. a device for interrupting an electric circuit to prevent excessive current, as that caused by a short circuit, from damaging the apparatus in the circuit or from causing a fire.

2. Also called trading halt or trading curb.  Stock Exchange. a temporary halt in trading automatically imposed when stock prices reach a predetermined level, as to check panic selling.

3. a lockdown or set of tight restrictions imposed for a fixed, usually short period to halt the spread of a highly transmissible infection (often used attributively).

   Circuit breakers only succeed if additional measures are taken, such as contact tracing and increased testing.

4. Australia, New Zealand. an activity serving to relieve or distract from stresses that might otherwise overwhelm.

   Sometimes a day out of the office is the best circuit breaker after a tense week.

5. any property-tax relief measure that reduces or limits property taxes for certain eligible taxpayers, as those with low income or the elderly.

---

circuit breaker British  

noun

1. Sometimes shortened to: breaker.  a device that under abnormal conditions, such as a short circuit, interrupts the flow of current in an electrical circuit Compare fuse 2

---

circuit breaker Scientific  

1. A switch that automatically interrupts the flow of electric current if the current exceeds a preset limit, measured in amperes. Circuit breakers are used most often as a safety precaution where excessive current through a circuit could be hazardous. Unlike fuses, they can usually be reset and reused.

---

Etymology

Origin of circuit breaker

An Americanism dating back to 1870–75

Example Sentences

If you have to evacuate, you should disconnect all electrical appliances or turn off electric circuits at the fuse box or circuit breaker panel.

From Los Angeles Times • Dec. 23, 2025

None other than Justice Antonin Scalia wrote that the jury functions as “a circuit breaker in the state’s machinery of justice.”

From Slate • Nov. 7, 2025

She said the Welsh cabinet had made a "brave decision" in introducing its own short autumn lockdown following scientific advice calling for a "circuit breaker".

From BBC • Mar. 12, 2024

If your circuit breaker goes off frequently, check how much is plugged into that particular circuit and rethink your arrangements.

From Seattle Times • Dec. 20, 2023

Once I reached the laundry room, I scrambled up the ladder and flipped the circuit breaker switch twice.

From "Sir Fig Newton and the Science of Persistence" by Sonja Thomas