Source : Webster's Revised Unabridged Dictionary (1913)

Conductor \Con*duct"or\ (k[o^]n*d[u^]k"t[~e]r), n. [LL., a
   carrier, transporter, L., a lessee.]
   1. One who, or that which, conducts; a leader; a commander; a
      guide; a manager; a director.

            Zeal, the blind conductor of the will. --Dryden.

   2. One in charge of a public conveyance, as of a railroad
      train or a street car. [U. S.]

   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}.

   {Prime conductor} (Elec.), the largest conductor of an
      electrical machine, serving to collect, accumulate, or
      retain the electricity.

Source : WordNet®

conductor
     n 1: the person who leads a musical group [syn: {music director},
           {director}]
     2: a device designed to transmit electricity, heat, etc.
     3: a substance that readily conducts e.g. electricity and heat
        [ant: {insulator}]
     4: the person who collects fares on a public conveyance