Conductor

n.
  1. One who, or that which, conducts; a leader; a commander; a guide; a manager; a director.
  2. One in charge of a public conveyance, as of a railroad train or a street car.
  3. (Mus.) The leader or director of an orchestra or chorus.
  4. (Physics) A substance or body capable of being a medium for the transmission of certain forces, esp. heat or electricity; specifically, a lightning rod.
  5. (Surg.) A grooved sound or staff used for directing instruments, as lithontriptic forceps, etc.; a director.
  6. (Arch.) Same as Leader.
    7. Prime conductor (Elec.),
    the largest conductor of an electrical machine, serving to collect, accumulate, or retain the electricity.