Which word best describes someone who has an insatiable appetite for knowledge or food?

The word "voracious" is indeed the best fit for someone with an insatiable appetite for knowledge or food. It conveys a strong and enthusiastic eagerness, often implying an unquenchable thirst or desire for something. When applied to knowledge, it suggests a person who is constantly seeking out new information, insights, and learning opportunities. Similarly, in the context of food, it describes someone who eats eagerly and greedily, reflecting an intense desire for sustenance.

In contrast, "diaphanous" refers to something that is light, delicate, or translucent, typically used to describe fabrics or materials. It does not capture the idea of a strong desire or appetite. "Dilatory" pertains to delaying or procrastinating, and does not correlate with the concept of appetite, whether for knowledge or food. Lastly, "desuetude" refers to a state of disuse or inactivity, which does not relate to a person actively seeking or consuming knowledge or food. Thus, "voracious" is the most appropriate choice in the context given.