Définitions
1.AdjectiveNot tractable; not able to be managed, controlled, governed or directed.
2.AdjectiveNot able to be solved in polynomial time; too difficult to attempt to solve.
3.AdjectiveDifficult to deal with, solve, or manage.
4.AdjectiveStubborn; obstinate.
5.AdjectiveDifficult to treat (of a medical condition).