noun (n)

• a resentment strong enough to justify retaliation(noun.feeling)

  Synonym:
  grudge, score
  

  source: wordnet30
• an allegation that something imposes an illegal obligation or denies some legal right or causes injustice(noun.communication)

  source: wordnet30
• a complaint about a (real or imaginary) wrong that causes resentment and is grounds for action(noun.communication)

  source: wordnet30
• A cause of uneasiness and complaint; a wrong done and suffered; that which gives ground for remonstrance or resistance, as arising from injustice, tyranny, etc.; injury.(noun)

  source: webster1913