1b3b5bb7
Fig. 1 · Adim7 on the keyboard

piano chord

Adim7

A1C♭3E♭♭5G♭♭♭7

Three minor thirds stacked. The seventh is doubly diminished, which is why it is written with a double flat.

on guitaron ukulelethe scale

What is true of it

Adim7 is A, C, E♭ and G♭ — 1, b3, b5 and bb7 counted from A.

A in other shapes

A7dominant seventhAmaj7major seventhAm7minor seventhAmajorAmminorAdimdiminished

Cdim7C♯dim7D♭dim7Ddim7D♯dim7E♭dim7Edim7Fdim7all 374