noun (n)

• the fundamental assumptions from which something is begun or developed or calculated or explained(noun.cognition)

  Synonym:
  base, basis, foundation, fundament, groundwork
  

  source: wordnet30
• a stone in the exterior of a large and important building; usually carved with a date and laid with appropriate ceremonies(noun.artifact)

  source: wordnet30
• a stone at the outer corner of two intersecting masonry walls(noun.artifact)

  source: wordnet30