Electrical[]
A circuit is "[a] conductor or a system of conductors through which electric current flows."[1]
Electronics[]
See Integrated circuit.
Telecommunications[]
A circuit is the complete transmission path between two terminals over which one-way or two-way communication may be provided. A circuit may provide one or more channels.
A circuit is
| “ | an electrical connection whose voltage could be modulated on one end in ways that could be detected and interpreted on the other; thus the telegraph and the telephone. In a circuit, sender and receiver are directly connected in real time although neither need be human, as the invention of the facsimile proved.[2] | ” |