noun (n)

• a particular environment or walk of life(noun.state)

  Synonym:
  area, arena, field, orbit, sphere
  

  source: wordnet30
• territory over which rule or control is exercised(noun.location)

  Example:
  His domain extended into Europe.
  

  Synonym:
  demesne, land
  

  source: wordnet30
• (mathematics) the set of values of the independent variable for which a function is defined(noun.group)

  Synonym:
  domain of a function
  

  source: wordnet30
• people in general; especially a distinctive group of people with some shared interest(noun.group)

  Synonym:
  world
  

  source: wordnet30
• the content of a particular field of knowledge(noun.cognition)

  Synonym:
  knowledge base, knowledge domain
  

  source: wordnet30
• Dominion; empire; authority.(noun)

  source: webster1913