What term is defined as the central idea or essence of something?

The term that represents the central idea or essence of something is "gist." It refers to the main point or the underlying meaning of a discussion, text, or concept, capturing its fundamental essence without getting distracted by extraneous details. When someone is looking to summarize a piece of information, they often aim to convey its gist—essentially distilling the content down to its most critical elements.

In contrast, the other terms do not align with this definition. "Glut" refers to an excessive supply of something, "gouge" typically denotes the act of cutting or chipping out material or can mean to overcharge someone, and "gloat" involves expressing joy or satisfaction in one's own success or someone else's misfortune. None of these convey the idea of capturing the essence or main idea of a subject.