Other forms: circuits
A circuit is the complete loop electricity travels round to make something work. Battery, wire, bulb and back to the battery — break the loop anywhere and the light goes out.
That loop runs through every other use. A circuit is a lap or a round trip, so runners do three circuits of the field, and a racing circuit is the closed track itself. In a gym, circuit training moves you round a set of exercises and back to the first. Judges once rode a circuit of towns to hear cases, which is why American appeal courts are still circuit courts and why comedians speak of the comedy circuit, the same places visited again and again. Electricians live inside the word: a short circuit, a circuit breaker, a printed circuit board. The adjective circuitous means roundabout, in a way that wastes time.
1nouncircuitA complete path around which an electric current flows.
“One loose wire and the whole circuit is dead.”
2nountrackA closed track used for racing.
“The car completed the circuit in under two minutes.”
synonyms: track
3nounlapOne journey round something; a lap.
“The guard makes a circuit of the building every hour.”
4nounregularA regular set of places or events visited in turn as part of a job.
“She plays the folk festival circuit every summer.”
circuit is a closed loop.
Latin circuitus meant 'a going round', from circum, 'around', and īre, 'to go'. Old French passed it on unchanged, and Middle English took it whole. Electricity in a wire, a runner on a track, a judge riding between towns — a circuit is still a going round that ends where it began.
Latin
circuitus — a going round
Old French
circuit
Middle English
circuit
English, today
circuit
Built from
From Middle English circuit, from Old French circuit, from Latin circuitus (“a going round”), from circuire (“go round”), from circum (“around”) + ire.
Etymology from Wiktionary, CC BY-SA