subject matter

Matter under consideration in a written work or speech; a theme.

noun

What a speech, piece of writing, or artistic work is about: argument, matter, point, subject, text, theme, topic. See meaning.

The thing in dispute; the nature of the cause of action; "the real issue of fact or law presented for trial as between those parties" 62 P. 2d 1248, 1252; the object of a contract.

The noun has one meaning:

Meaning #1: what a communication that is about something is about
  Synonyms: message, content, substance