A Theme

1. A subject, now especially of a talk or an artistic piece; a topic.
2. A recurring idea; a motif.
   1. A concept with multiple instantiations.
   2. Any of various colors, or color palettes, in which a design is offered; (graphical user interface) any of various skins for an app, affecting the visuals and perhaps other elements such as sound effects.

Synonym: colorway

3. (dated) An essay written for school.
4. (music) The main melody of a piece of music, especially one that is the source of variations.
5. (film, television) A song, or a snippet of a song, that identifies a film, a TV program, a character, etc. by playing at the appropriate time.
6. (grammar) The stem of a word.
7. (linguistics) thematic relation of a noun phrase to a verb.
8. (linguistics) Theta role in generative grammar and government and binding theory.
9. (linguistics) Topic, what is generally being talked about, as opposed to rheme.
10. A regional unit of organisation in the Byzantine empire.