intractable

Adjective

intractable (comparative more intractable, superlative most intractable)

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, Edsger W. Dijkstra, The Humble Programmer (EWD340)
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, Robert Jackall, “Chapter 1: Moral Probations, Old and New”, in Moral Mazes: The World of Corporate Managers, Twentieth Anniversary edition, →ISBN, page 12
4. Stubborn; obstinate. (of a person)
5. Difficult to treat (of a medical condition).