noun (n)

• the act of entering some territory or domain (often in large numbers)(noun.act)

  Example:
  The incursion of television into the American living room.
  

  source: wordnet30
• an attack that penetrates into enemy territory(noun.act)

  Synonym:
  penetration
  

  source: wordnet30
• the mistake of incurring liability or blame(noun.act)

  source: wordnet30
• A running into; hence, an entering into a territory with hostile intention; a temporary invasion; a predatory or harassing inroad; a raid.(noun)

  source: webster1913