What does the term illicit mean?

The term "illicit" specifically refers to something that is illegal or not permitted by law or societal norms. It is often used to describe actions, activities, or substances that are against the law, such as illicit drug use or illicit affairs. This understanding highlights the term's association with prohibited behavior and reinforces the concept that it carries a negative connotation in legal or moral contexts.

The other options convey meanings that do not align with the definition of "illicit." Describing something as well-known and distinguished implies a positive recognition, while causing something to diminish refers to a reduction in quantity or quality, and treating guests well relates to hospitality, none of which pertain to the notion of legality or prohibition. Therefore, the correct selection is indeed the one that identifies "illicit" as meaning illegal.