What term describes something that is difficult to understand?

The term that best describes something that is difficult to understand is "inscrutable." This word conveys the idea that something is so mysterious or unfathomable that it evades comprehension entirely. Whether referring to a person’s expression or a complex text, inscrutable indicates that the meaning is not easily discernible and requires more effort to decipher.

"Ambiguous" refers to something that can be interpreted in multiple ways, which can imply difficulty in understanding, but it doesn’t inherently suggest a lack of comprehensibility.

"Opaque" often describes objects that are not transparent, making it challenging to see through them or understand what lies beyond, but it is less frequently used in a figurative sense related to comprehension.

"Cryptic" shares similarities with inscrutable in that it denotes something that is mysterious or has a hidden meaning. However, it often suggests that while something may be difficult to grasp, it still contains some level of potential insight or understanding beneath the surface.

In contrast, "inscrutable" emphasizes a more profound level of obscurity and difficulty in understanding, making it the most appropriate choice in this context.