A topic of discourse or discussion. See Synonyms at subject. A subject of artistic representation. An implicit or recurrent idea; a motif: a theme of powerlessness that runs through the diary; a party with a tropical island theme. A short composition assigned to a student as a writing exercise. Music The principal melodic phrase in a composition, especially a melody forming the basis of a set of variations. Linguistics A stem. Linguistics See topic. Usage Problem To provide with a particular topic or motif. See Usage Note at themed.