noun (n)

• a ghostly appearing figure(noun.person)

  Example:
  We were unprepared for the apparition that confronted us.
  

  Synonym:
  fantasm, phantasm, phantasma, phantom, specter, spectre
  

  source: wordnet30
• the appearance of a ghostlike figure(noun.event)

  Example:
  I was recalled to the present by the apparition of a frightening specter.
  

  source: wordnet30
• something existing in perception only(noun.cognition)

  Example:
  A ghostly apparition at midnight.
  

  Synonym:
  fantasm, phantasm, phantasma, phantom, shadow
  

  source: wordnet30
• an act of appearing or becoming visible unexpectedly(noun.act)

  Example:
  Natives were amazed at the apparition of this white stranger.
  

  source: wordnet30
• The act of becoming visible; appearance; visibility.(noun)

  source: webster1913