noun (n)

• the position of a prominent or well-known object in a particular landscape(noun.location)

  Example:
  The church steeple provided a convenient landmark.
  

  source: wordnet30
• an event marking a unique or important historical change of course or one on which important developments depend(noun.event)

  Synonym:
  turning point, watershed
  

  source: wordnet30
• a mark showing the boundary of a piece of land(noun.communication)

  source: wordnet30
• an anatomical structure used as a point of origin in locating other anatomical structures (as in surgery) or as point from which measurements can be taken(noun.body)

  source: wordnet30
• A mark to designate the boundary of land; any mark or fixed object (as a marked tree, a stone, a ditch, or a heap of stones) by which the limits of a farm, a town, or other portion of territory may be known and preserved.(noun)

  source: webster1913