1 a major object of interest or concern (as in a discussion or artistic composition)

  • this dance piece deals with the timeless themes of birth and death

2 a short piece of writing done as a school exercise

  • please write a one page theme on the main character of this book

3 a short piece of writing typically expressing a point of view

  • the magazine will award a scholarship to the student who writes the best theme on the concept of personal freedom

Source