The D Diminished Seventh chord is composed of the Root, Minor Third, diminished Fifth, and Diminished Seventh The Ddim7 chord is spelled in the following ways D Diminished Seventh D Dim D Diminished 7 D O7 Ddim7 The notes of this chord are D, F, Ab, and Cb Diminished 7th chords introduce in your progressions a great sense of tension and