noun (n)

• the state of being hollow: having an empty space within(noun.state)

  Antonym:
  solidity
  

  source: wordnet30
• the property of having a sunken area(noun.attribute)

  source: wordnet30
• the quality of not being open or truthful; deceitful or hypocritical(noun.attribute)

  Synonym:
  falseness, insincerity
  Antonym:
  sincerity
  

  source: wordnet30
• State of being hollow.(noun)

  source: webster1913