The term 'central theme' can refer to a few different concepts. The most common is the main idea or message of a piece of literature, which can be expressed through a KEYNOTE, MOTIF, or GIST. A KEYNOTE is a word or phrase that serves as the main focus of a work and is often repeated throughout. A MOTIF is a recurring element in a work that helps to reinforce the central theme. Finally, the GIST is the essential point or main idea of a work. All three of these elements help to convey the central theme of a work.