noun (n)

• the quality of being resistant to variation(noun.attribute)

  Synonym:
  invariability, invariableness
  Antonym:
  variability, variableness, variance
  

  source: wordnet30
• the nature of a quantity or property or function that remains unchanged when a given transformation is applied to it(noun.attribute)

  Example:
  The invariance of the configuration under translation.
  

  source: wordnet30
• The property of remaining invariable under prescribed or implied conditions.(noun)

  source: webster1913