Guitar chords in the key of C major:
C Dm Em F G Am Bdim

Chord Cdim7 (11th fret) notes: A, Eb, Gb, C and Eb. You should not play the 6th string.

This chord is played by placing a barre on fret eleven with your index finger.

Cdim7 - C diminished seventh guitar chord's alternative names: C°, C°7, Co7, C7dim. See also: Cdim and Cm7b5.

Steps: 1-b3-b5-6(or bb7).
1(C), b3(D#/Eb), b5(F#/Gb), 6(A).