Wicked Problem
Etymology
Coined by design theorists Horst Rittel and Melvin Webber in a 1973 paper on planning. "Wicked" here carries its older sense of resistant, intractable, vicious the way a thorn is — not morally evil — describing problems that won’t hold still. They opposed such problems to the "tame" ones of science and math.
noun phrase · /WIK-id PROB-lem/
A problem so tangled and shifting that it resists clear definition, has no final solution, and changes as you try to solve it.
What it names
A label for the messes that engineering instincts fail on — climate, poverty, urban planning — where there’s no stopping rule, every attempt reshapes the problem, and "solved" is never available, only "better or worse."
Example
Homelessness is a wicked problem: fix the housing supply and you’ve reshaped, not closed, the question.
Related idea
Its trouble compounds through second-order effects — each intervention spawns new consequences that redefine the problem, which is precisely what keeps it from ever being tame.