conductor

noun

• 1a person who directs the performance of an orchestra or choir: he was appointed principal conductor of the Berlin Symphony Orchestra

• 2British a person who collects fares and sells tickets on a bus.
• North American a guard on a train.

• 3 Physics a material or device that conducts or transmits heat or electricity, especially when regarded in terms of its capacity to do this:most polymers are poor conductors
• short for lightning conductor.

• 4British a person who is trained to provide conductive education.