'Extended' tends to indicate chord notes past the seventh.willdub1 wrote: wouldn't a major 7th chord voiced without the third be an extended chord?
If you mean C, B a seventh up from the C and the G above that, you could be seeing someone's idea of a G triad with a C bass, which in terms of spelling in thirds, C^9 implied. But this construction in itself is open for interpretation. The thing I want to say to you is have a musical idea _before_ the 'theory'. Theory is a cart here, it doesn't pull the horse. No one knows what it *is* outside of some music.