noun (n)

• the condition of being pressed closely together and firmly fixed(noun.state)

  source: wordnet30
• a disorder in which feces are impacted in the lower colon(noun.state)

  source: wordnet30
• a disorder in which a tooth is so crowded in its socket that it cannot erupt normally(noun.state)

  Synonym:
  impacted tooth
  

  source: wordnet30
• a sharp collision produced by striking or dashing against something(noun.act)

  Synonym:
  impingement
  

  source: wordnet30
• The driving of one fragment of bone into another so that the fragments are not movable upon each other; as, impaction of the skull or of the hip.(noun)

  source: webster1913