A specific chord voicing cannot always be accurately captured in a chord symbol. This is one of these instances. What you basically have here is a shell rootless G13 chord (FBE) with an Ab in the bass. You CAN call it a G13/Ab(no root) but don’t expect it will always sound the way you want if someone else reads and interprets that chord. For example, some players might choose to add a 5th or a 9th to it.

This chord has a diminished quality to it. If you replace the E with a D it is simply a Abo7: 4x343x. There are times when a diminished chord has non-diminished chord tones added to it. If you spell it from the F it is a Fo(maj7)/Ab (1st inversion). A M7 note is sometimes used as either a chord tone or a melody note in diminished chords (“Spring is Here” and “Stella By Starlight*, both in bar 1). You could also spell it from the root: Abo(b6,no 5). Both of these are also accurate but awkward chord symbols so pick your poison. Personally I prefer the G13/Ab(no root). I think this would best be understood by another jazz or Brazilian guitarist and in most instances I think the “no root” designation would be a given.

This chord does resolve to a C in a slightly unusual way because of the Ab root but in making my case for the diminished quality you will see it also resolves nicely to Amaj7 or Am7.


*In the case of “Stella”, the original first chord is a Io, not the 2-5 commonly used in fake books