Which word describes something intended to instruct?

The term "didactic" is used to describe something that is intended to instruct or teach. It often pertains to educational content that aims to convey moral or philosophical lessons. The roots of the word trace back to pedagogical methods, highlighting its association with teaching. In literature, for instance, didactic works are those that are crafted with the underlying goal of imparting knowledge or informing the audience about certain principles or values.

In contrast, the other options do not align with the idea of instruction. "Ephemeral" refers to things that are short-lived or temporary, lacking any inherent educational purpose. "Acerbic" describes a sharp or biting tone, typically in speech or writing, but does not imply any intention to teach. Similarly, "cynical" denotes a distrusting or questioning attitude towards others' motives, which does not provide a framework for teaching or instruction. Therefore, "didactic" stands out as the term that explicitly captures the essence of something designed to educate or provide instruction.