noun (n)

• the muscle tone of healthy tissue(noun.attribute)

  Example:
  His muscular firmness.
  

  Synonym:
  soundness
  Antonym:
  unsoundness
  

  source: wordnet30
• the trait of being resolute(noun.attribute)

  Synonym:
  firmness of purpose, resoluteness, resolution, resolve
  Antonym:
  irresoluteness, irresolution
  

  source: wordnet30
• the property of being unyielding to the touch(noun.attribute)

  source: wordnet30
• the quality of being steady or securely and immovably fixed in place(noun.attribute)

  Synonym:
  steadiness
  Antonym:
  ricketiness, unsteadiness
  

  source: wordnet30
• The state or quality of being firm.(noun)

  source: webster1913