Jazz theory: Dim 7th chord

[mijulan]

In Jazz it is said that a dim 7th chord can be used as a passing chord between two chords. Is it only a dim 7th chord? Can another 7th chord be used? If not why not? I really want to understand this. Thanks.

[lelle]

Can you explain what you/they mean by a passing chord?

Often dim 7th chords function as dominants where you have removed the root note and added a flattened 9th. For example, a dim 7th chord that would function similarly to the dominant of C major would be B-D-F-Ab - it's the same as a G7b9 chord with the root note - i.e. G - removed (G major is the dominant).

But wait, there is more! The exact same pitches can also function as rootless dominant 7b9 chords to other tonics too. For example D-F-Ab-Cb - enharmonically equivalent to B-D-F-Ab - can function as the dominant to an Eb chord. This way, you can use dim chords to modulate/pivot between different keys quite neatly.

If the above is what is meant with "passing chords" then of course you can use other chords as passing chords too. The most obvious would be the normal dominant 7th chord. Example C -> A7 -> Dm (A7 is the passing chord to get you from C to Dm).