intractable

adjective5

1. •
   Not tractable; not able to be managed, controlled, governed or directed.

   • And I cannot but expect that this will repeatedly lead to the discovery that an initially intractable problem can be factored after all. — 1972
2. •
   Not able to be solved in polynomial time; too difficult to attempt to solve.
3. •
   Difficult to deal with, solve, or manage. (of a problem)

   • Work—bureaucratic work in particular—poses a series of intractable dilemmas that often demand compromises with traditional moral beliefs. — 1988
4. •
   Stubborn; obstinate. (of a person)
5. •
   Difficult to treat (of a medical condition).