The Collaborative International Dictionary of English v.0.48:

Tractability \Tract`a*bil"i*ty\, n. [L. tractabilitas: cf.F.
   tractabilite.]
   The quality or state of being tractable or docile; docility;
   tractableness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tractability
    n 1: the trait of being easily persuaded [syn: tractability,
         tractableness, flexibility] [ant: intractability,
         intractableness]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "tractability":
   acquiescence, adaptability, agreeability, agreeableness, alacrity,
   amenability, ardor, bendability, biddability, cheerful consent,
   compliableness, compliance, consent, cooperativeness, docility,
   ductibility, ductility, eagerness, elasticity, enthusiasm,
   extendibility, extensibility, facility, favorable disposition,
   favorableness, fictility, flexibility, flexility, flexuousness,
   formativeness, forwardness, gameness, give, goodwill,
   impressionability, limberness, litheness, malleability,
   moldability, plasticity, pliability, pliancy, promptness,
   readiness, receptive mood, receptiveness, receptivity,
   responsiveness, right mood, sensibility, sensitiveness, sequacity,
   servility, springiness, submissiveness, subservience, suppleness,
   susceptibility, tensileness, tensility, tractility, ungrudgingness,
   unloathness, unreluctance, willing ear, willing heart, willingness,
   willowiness, yieldingness, zeal, zealousness