noun (n)

• the physical property of being stiff and resisting bending(noun.attribute)

  Synonym:
  rigidness
  

  source: wordnet30
• the quality of being rigid and rigorously severe(noun.attribute)

  Synonym:
  inflexibility, rigidness
  Antonym:
  flexibility, flexibleness
  

  source: wordnet30
• The quality or state of being rigid; want of pliability; the quality of resisting change of form; the amount of resistance with which a body opposes change of form; -- opposed to flexibility, ductility, malleability, and softness.(noun)

  source: webster1913