1b3b5
Fig. 1 · Cdim on the keyboard

piano chord

Cdim

C1E♭♭3G♭♭5

Two minor thirds stacked. The fifth is diminished, so it cannot be dropped without losing the chord.

on guitaron ukulelethe scale

What is true of it

Cdim is C, E♭ and G♭ — 1, b3 and b5 counted from C.

C in other shapes

CmajorCmminorCaugaugmentedC5power chordCsus2suspended secondCsus4suspended fourth

C♯dimD♭dimDdimD♯dimE♭dimEdimFdimF♯dimall 374