Which word describes something intricate and complex?

The word "involute" is the most fitting choice for describing something intricate and complex. This term typically refers to things that are coiled, twisted, or convoluted in a way that makes them complicated and difficult to navigate or understand. In various disciplines, such as mathematics or biology, "involute" conveys an idea of layered or sophisticated structures or patterns, emphasizing the complexity inherent in their arrangement or function.

In contrast, "inveterate" generally describes an established habit or long-standing condition, often having more to do with persistence than intricacy. "Minatory" refers to something that is threatening or menacing, which does not relate to complexity at all. "Jejune," on the other hand, describes something that is simplistic or lacking in substance, highlighting a deficiency rather than intricacy or depth. This makes "involute" the most appropriate choice for describing something intricate and complex.