noun (n)

• emotions experienced when not in a state of well-being(noun.feeling)

  Synonym:
  unhappiness
  Antonym:
  happiness
  

  source: wordnet30
• the state of being sad(noun.state)

  Example:
  She tired of his perpetual sadness.
  

  Synonym:
  sorrow, sorrowfulness
  

  source: wordnet30
• the quality of excessive mournfulness and uncheerfulness(noun.attribute)

  Synonym:
  gloominess, lugubriousness
  

  source: wordnet30
• Heaviness; firmness.(noun)

  source: webster1913