noun (n)

• the person who leads a musical group(noun.person)

  Synonym:
  director, music director
  

  source: wordnet30
• a substance that readily conducts e.g. electricity and heat(noun.substance)

  Antonym:
  dielectric, insulator, nonconductor
  

  source: wordnet30
• the person who collects fares on a public conveyance(noun.person)

  source: wordnet30
• a device designed to transmit electricity, heat, etc.(noun.artifact)

  source: wordnet30
• One who, or that which, conducts; a leader; a commander; a guide; a manager; a director.(noun)

  source: webster1913