Why is the ninth month called September?
1520s, "one who leads or guides," from Middle French conductour (14c., Old French conduitor), from Latin conductor "one who hires, contractor," in Late Latin "a carrier," from conductus, past participle of conducere (see conduce).
Earlier in same sense was conduitour (early 15c., from Old French conduitor). Meaning "leader of an orchestra or chorus" is from 1784; meaning "one who has charge of passengers and collects fares on a railroad" is 1832, American English. Physics sense of "object or device that passes heat" is from 1745; of electricity from 1737.
conductor con·duc·tor (kən-dŭk'tər)
A substance or medium that conducts heat, light, sound, or especially an electric charge.
An instrument or probe having a groove along which a knife is passed in slitting open a sinus or fistula; a grooved director.
A material or an object that conducts heat, electricity, light, or sound. Electrical conductors contain electric charges (usually electrons) that are relatively free to move through the material; a voltage applied across the conductor therefore creates an electric current. Insulators (electrical nonconductors) contain no charges that move when subject to a voltage. Compare insulator. See also resistance, superconductivity.