noun (n)

• lack of depth of knowledge or thought or feeling(noun.attribute)

  Synonym:
  superficiality
  Antonym:
  profoundness, profundity
  

  source: wordnet30
• the quality of lacking physical depth(noun.attribute)

  Example:
  Take into account the shallowness at that end of the pool before you dive.
  

  Antonym:
  deepness, profoundness, profundity
  

  source: wordnet30
• Quality or state of being shallow.(noun)

  source: webster1913