Noun
1. a domain in which something is dominant;
"the untroubled kingdom of reason""a land of make-believe""the rise of the realm of cotton in the south"2. a country with a king as head of state
3. the domain ruled by a king or queen
4. a monarchy with a king or queen as head of state
5. one of seven biological categories: Monera or Protoctista or Plantae or Fungi or Animalia
6. a basic group of natural objects