noun (n)

• the state in which a substance has no tendency to flow under moderate stress; resists forces (such as compression) that tend to deform it; and retains a definite size and shape(noun.state)

  Synonym:
  solid, solid state
  

  source: wordnet30
• the consistency of a solid(noun.attribute)

  Synonym:
  solidity
  Antonym:
  porosity, porousness
  

  source: wordnet30
• the quality of being substantial or having substance(noun.attribute)

  Synonym:
  substantiality, substantialness
  Antonym:
  insubstantiality
  

  source: wordnet30
• the quality of being solid and reliable financially or factually or morally(noun.attribute)

  Example:
  The solidness of her faith gave her enduring hope.
  

  source: wordnet30
• State or quality of being solid; firmness; compactness; solidity, as of material bodies.(noun)

  source: webster1913