conductor

noun

1. One who conducts or leads; a guide; a director.

   “[…]Zeal, the blind conductor of the will;”

2. A person who conducts an orchestra, choir or other music ensemble; a professional whose occupation is conducting.
3. A person who takes tickets on public transportation and also helps passengers.

   “train conductor”

   “tram conductor”

   “"[…] And one of the things that makes me feel safe is when I see the conductor."”

4. Something that can transmit electricity, heat, light, or sound.

   “Falling conductors may come in contact with grounded objects or puddles of water.”

   “The failure of HIF detection leads to potential hazard to human beings and potential fire. HIFS are usually caused by falling conductors coming into contact with a surface having poor conductivity.”

5. An ideal of a ring that measures how far it is from being integrally closed

   “If c is the conductor ideal for R in R then prime ideals not containing c correspond to localizations yielding discrete valuation rings.”

6. A grooved sound or staff used for directing instruments, such as lithontriptic forceps; a director.
7. A leader.