The Collaborative International Dictionary of English v.0.48:

Manageable \Man"age*a*ble\, a.
   Such as can be managed or used; suffering control;
   governable; tractable; subservient; as, a manageable horse.
   [1913 Webster]

   Syn: Governable; tractable; controllable; docile.
        [1913 Webster] -- Man"age*a*ble*ness, n. --
        Man"age*a*bly, adv.
        [1913 Webster]

WordNet (r) 3.0 (2006):

manageable
    adj 1: capable of being managed or controlled [ant: difficult,
           unmanageable]
    2: capable of existing or taking place or proving true; possible
       to do [syn: accomplishable, achievable, doable,
       manageable, realizable]

Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "manageable":
   actable, adaptable, amenable, budget, cheap, compassable,
   compliant, controllable, convenient, corrigible, doable, docile,
   domesticable, domitable, ductile, easy, economic, economy,
   feasible, flexible, foolproof, frugal, governable, handleable,
   handy, inexpensive, low, low-priced, malleable, maneuverable,
   manipulable, manipulatable, moderate, modest, negotiable, nominal,
   operable, operatable, performable, pliable, pliant, practicable,
   practical, reasonable, restrainable, sensible, shabby, shoddy,
   submissive, tamable, tame, teachable, token, tractable, trainable,
   unexpensive, untroublesome, viable, wieldable, wieldy,
   within means, workable, worth the money, yielding