A telecommunication circuit is defined as follows:

  1. The complete path between two terminals over which one-way or two-way communications may be provided. See communications protocol.
  2. An electronic path between two or more points, capable of providing a number of channels.
  3. A number of conductors connected together for the purpose of carrying an electric current.
  4. An electronic closed-loop path among two or more points used for signal transfer.
  5. A number of electrical components, such as resistors, inductances, capacitors, transistors, and power sources connected together in one or more closed loops.

Source: from Federal Standard 1037C and from MIL-STD-188