What term is used for a script that is difficult to decipher, utilizing pictorial symbols?

The term "hieroglyph" is specifically used to describe a writing system that utilizes pictorial symbols to represent words, sounds, or concepts. This form of writing is famously associated with ancient Egyptian literature and inscriptions, where symbols could depict objects and ideas, allowing for deep meanings and cultural narratives to be conveyed visually. Hieroglyphs often comprise a complex system that can represent both phonetic sounds and semantic meaning, making them a form of script that is indeed difficult to decipher without adequate knowledge of the language and symbols used.

In contrast, the other terms do not relate to this specific concept. "Hierarchical" pertains to a system organized in a ranked order, not to writing or scripts. "Hypothetical" refers to something that is based on a hypothesis or conjecture, and does not evoke the idea of a written language or symbols. Lastly, "holographic" relates to holograms and the technology used to produce 3D images, thus it too does not fit within the context of writing or deciphering scripts.