Is it true that the melody consists GENERALLY of single notes ?

Yes, assuming a series of single notes.





When you add additional notes, you add harmony or chords.Is it true that the melody consists GENERALLY of single notes ?
Music theory is defined by the general consensus of music theoreticians.





My guess is that if you, for example, created a melody in major 3rds the whole way through, and then developed that melody, always keeping it in thirds, then no, the melody would not be comprised of single notes. Though you can easily make the argument that one of the lines is just a harmony, but it's really the composer's intention that defines if he/she means it to be a melody in thirds, or a melody with a harmony of a third above or below it.





But if the harmony is not a consistent interval, it's definitely a line of harmony, or a counter-melody.Is it true that the melody consists GENERALLY of single notes ?
Yes, because extra notes added to the melody are generally considered as harmony.





There can be exceptions to this rule though. One thing that immediately popped into my mind is a theme that John Williams uses for a big battle in his score for Star Wars Episode III. There is a cluster (multiple pitches adjacent to one another that are played at the same time) that is used as if it were a single pitch every time the theme occurs.





Situations like this are very rare though. In fact, I honestly can't think of any other examples.
True. Perhaps part of the definition of a melody? A second tone would be considered the harmony.
Not even ';generally';. It is ';specifically';





... otherwise there is harmony.