What word means lacking sense or substance; empty or stupid?

The word that means lacking sense or substance; empty or stupid is inane. This term is often used to describe something that is foolish or lacking in meaningful content. In various contexts, it can refer to ideas, conversations, or behaviors that are perceived as silly or nonsensical, highlighting a deficiency in depth or seriousness.

In contrast, incessant refers to something that continues without interruption, impermeable describes something that does not allow passage, often in terms of liquids or gases, and incumbent refers to the current holder of an office or position. None of these terms conveys the notion of emptiness or lack of intelligence like inane does, making it the most appropriate choice in this context.