What is the meaning of kingdom?

noun

• A domain in which something is dominant.
  • usage: "the untroubled kingdom of reason"; "a land of make-believe"; "the rise of the realm of cotton in the south"
  • synonyms: land, realm
• A country with a king as head of state.
• The domain ruled by a king or queen.
  • synonyms: realm
• A monarchy with a king or queen as head of state.
• The highest taxonomic group into which organisms are grouped; one of five biological categories: Monera or Protoctista or Plantae or Fungi or Animalia.
• A basic group of natural objects. .