What term is used to describe something that is not straightforward and highly intricate?

The term "tortuous" is an ideal choice for describing something that is not straightforward and is highly intricate. Originating from the Latin word "tortuosus," which means twisted or winding, it conveys a sense of complexity and indirectness. In various contexts, whether discussing a physical path or a convoluted argument, "tortuous" emphasizes the elaborate, often confusing nature of the subject.

In contrast, the other options do not convey the same meaning of complexity or intricacy. "Imprimatur" refers to an official approval or sanction, while "solicitous" denotes a state of being concerned or eager to help, neither of which implies intricacy. Lastly, "unfeigned" means genuine or sincere, lacking pretense, and does not carry any connotation of complication or winding nature. Thus, "tortuous" distinctly encapsulates the idea of something that is intricate and not straightforward.