theme

noun

• An main or dominant idea, motif
• A recurring melodic phrase or idea in a musical composition.
• Main idea of a work of art, writing, or music
• An idea that recurs in or pervades a work of art or literature.
• The style or idea behind something.
• The subject of a talk, piece of writing, exhibition, etc.
• Main subject being discussed or described
• A predesigned set of formatting elements for a website or software application.