The Collaborative International Dictionary of English v.0.48:

Flexibility \Flex`i*bil"i*ty\, n. [L. flexibilitas: cf. F.
   flexibilite.]
   The state or quality of being flexible; flexibleness;
   pliancy; pliability; as, the flexibility of strips of
   hemlock, hickory, whalebone or metal, or of rays of light.
   --Sir I. Newton.
   [1913 Webster]

         All the flexibility of a veteran courtier. --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

flexibility
    n 1: the property of being flexible; easily bent or shaped [syn:
         flexibility, flexibleness] [ant: inflexibility,
         inflexibleness]
    2: the quality of being adaptable or variable; "he enjoyed the
       flexibility of his working arrangement" [syn: flexibility,
       flexibleness] [ant: inflexibility, rigidity,
       rigidness]
    3: the trait of being easily persuaded [syn: tractability,
       tractableness, flexibility] [ant: intractability,
       intractableness]