theme

A subject, now especially of a talk or an artistic piece; a topic.

A concept with multiple instantiations.

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.

(dated) An essay written for school.

(music) The main melody of a piece of music, especially one that is the source of variations.

(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.

(grammar) The stem of a word.

(linguistics) thematic relation of a noun phrase to a verb.

(linguistics) Theta role in generative grammar and government and binding theory.

(linguistics) Topic, what is generally being talked about, as opposed to rheme.

A regional unit of organisation in the Byzantine empire.