noun (n)

• a window above a door that is usually hinged to a horizontal crosspiece over the door(noun.artifact)

  Synonym:
  transom, transom window
  

  source: wordnet30
• a window in a roof to admit daylight(noun.artifact)

  Synonym:
  skylight
  

  source: wordnet30
• a semicircular window over a door or window; usually has sash bars like the ribs of a fan(noun.artifact)

  source: wordnet30