The Collaborative International Dictionary of English v.0.48:

Tractable \Tract"a*ble\, a. [L. tractabilis, fr, tractare to
   draw violently, to handle, treat. See Treat, v. t.]
   1. Capable of being easily led, taught, or managed; docile;
      manageable; governable; as, tractable children; a
      tractable learner.
      [1913 Webster]

            I shall find them tractable enough.   --Shak.
      [1913 Webster]

   2. Capable of being handled; palpable; practicable; feasible;
      as, tractable measures. [Obs.] --Holder.
      [1913 Webster] --Tract"a*ble*ness, n. -- Tract"a/bly,
      adv.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tractable
    adj 1: easily managed (controlled or taught or molded);
           "tractable young minds"; "the natives...being...of an
           intelligent tractable disposition"- Samuel Butler [syn:
           tractable, manipulable] [ant: intractable]
    2: readily reacting to suggestions and influences; "a responsive
       student" [syn: amenable, tractable]