noun (n)

• the property possessed by a slope that is very gradual(noun.attribute)

  Synonym:
  gradualness
  Antonym:
  abruptness, precipitousness, steepness
  

  source: wordnet30
• acting in a manner that is gentle and mild and even-tempered(noun.attribute)

  Example:
  His fingers have learned gentleness.
  

  Synonym:
  mildness, softness
  

  source: wordnet30
• The quality or state of being gentle, well-born, mild, benevolent, docile, etc.; gentility; softness of manners, disposition, etc.; mildness.(noun)

  source: webster1913