Source : Webster's Revised Unabridged Dictionary (1913)

Intractable \In*tract"a*ble\, a. [L. intractabilis: cf. F.
   intraitable, formerly also intractable. See {In-} not, and
   {Tractable}.]
   Not tractable; not easily governed, managed, or directed;
   indisposed to be taught, disciplined, or tamed; violent;
   stubborn; obstinate; refractory; as, an intractable child.

   Syn: Stubborn; perverse; obstinate; refractory; cross;
        unmanageable; unruly; headstrong; violent; ungovernable;
        unteachable. -- {In*tract"a*ble*ness}, n. --
        {In*tract"a*bly}, adv.

Source : WordNet®

intractable
     adj : not tractable; difficult to manage or mold; "an intractable
           disposition"; "intractable pain"; "the most intractable
           issue of our era"; "intractable metal" [ant: {tractable}]