noun (n)

• a domain in which something is dominant(noun.state)

  Example:
  The rise of the realm of cotton in the south.
  

  Synonym:
  kingdom, land
  

  source: wordnet30
• the domain ruled by a king or queen(noun.location)

  Synonym:
  kingdom
  

  source: wordnet30
• a knowledge domain that you are interested in or are communicating about(noun.cognition)

  Example:
  It was a limited realm of discourse.
  The realm of the occult.
  

  Synonym:
  region
  

  source: wordnet30
• A royal jurisdiction or domain; a region which is under the dominion of a king; a kingdom.(noun)

  source: webster1913