guitar chord
Cdim
Two minor thirds stacked. The fifth is diminished, so it cannot be dropped without losing the chord.
Every fingering that fits a hand
x3454x
hard
xxa878
hard
89a8xx
moderate · barre
xxabdb
hard
What is true of it
Cdim is C, E♭ and G♭ — 1, b3 and b5 counted from C.
The easiest of the 4 fingerings below is x3454x: 4 fingers, held at the 3rd fret.
None of them uses an open string, so this chord moves up the neck unchanged — the same shape 1 fret higher is the chord a semitone above.
1 of the 4 need a barre.
2 strings stay silent.
Where its notes are on the neck
The brass dots are C, the root. Everything else is a chord tone with its degree printed in it.
With a different note underneath
Cdim/E♭
x6454x
Cdim/G♭
xx4542
An inversion is the same chord with a different note lowest. The name changes to a slash name because the bass is what a listener hears as the foundation.