noun (n)

• the head of a state government(noun.person)

  source: wordnet30
• a control that maintains a steady speed in a machine (as by controlling the supply of fuel)(noun.artifact)

  Synonym:
  regulator
  

  source: wordnet30
• One who governs; especially, one who is invested with the supreme executive authority in a State; a chief ruler or magistrate; as, the governor of Pennsylvania.(noun)

  source: webster1913