The Oxford Thesaurus An A-Z Dictionary of Synonyms - theme n.

1) subject(-matter) , topic, idea, notion, concept, thesis, text, thread, keynote, gist, core, substance, point, essence: What is the central theme of your article? 2 essay, paper, composition, review, article, story, piece, exposition, study, exercise, monograph, tract, thesis, dissertation, disquisition, treatise: I have to hand in two themes next week.