That cannot be solved, as a difficulty, question, problem, etc.; incapable of being resolved or explained; not susceptible of solution; unsolvable.

That cannot be resolved; not susceptible of resolution.

Of a problem: Incapable of being solved.

Insoluble, inexplicable; = indissoluble, adj. 5.

Of a mystery, etc.: unsolvable.

Incapable of being resolved or solved; insoluble.

= unsolvable, adj. 2.

That cannot be solved or explained; = insoluble, adj. 2.

Insoluble.

hen-and-(the)-egg: used as a modifier, designating the apparent paradox posed by the question ‘Which came first: the hen or the egg?’ (cf. quot…

That cannot be solved or explained; inexplicable, insoluble. rare.

Incapable of being solved or explained; insoluble.