an intricate problem; especially : a problem insoluble in its own terms —often used in the phrase cut the Gordian knot
gordian
noun(Gor-di-an knot)
a knot tied by Gordius, king of Phrygia, held to be capable of being untied only by the future ruler of Asia, and cut by Alexander the Great with his sword
gordian
idiom(Gor-di-an knot)
to solve a difficult problem in a very direct way by doing something forceful or extreme