The Collaborative International Dictionary of English v.0.48:

Stiffness \Stiff"ness\, n.
   The quality or state of being stiff; as, the stiffness of
   cloth or of paste; stiffness of manner; stiffness of
   character.
   [1913 Webster]

         The vices of old age have the stiffness of it too.
                                                  --South.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stiffness
    n 1: the physical property of being inflexible and hard to bend
    2: the property of moving with pain or difficulty; "he awoke
       with a painful stiffness in his neck"
    3: firm resoluteness in purpose or opinion or action; "a
       charming host without any touch of stiffness or pomposity"
    4: the inelegance of someone stiff and unrelaxed (as by
       embarrassment) [syn: awkwardness, clumsiness,
       gracelessness, stiffness]
    5: excessive sternness; "severity of character"; "the harshness
       of his punishment was inhuman"; "the rigors of boot camp"
       [syn: severity, severeness, harshness, rigor,
       rigour, rigorousness, rigourousness, inclemency,
       hardness, stiffness]