noun (n)

• the act of subjugating by cruelty(noun.act)

  Example:
  The tyrant's oppression of the people.
  

  Synonym:
  subjugation
  

  source: wordnet30
• the state of being kept down by unjust use of force or authority:(noun.state)

  Example:
  After years of oppression they finally revolted.
  

  source: wordnet30
• a feeling of being oppressed(noun.feeling)

  Synonym:
  oppressiveness
  

  source: wordnet30
• The act of oppressing, or state of being oppressed.(noun)

  source: webster1913