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The Diminished Seventh

diminished seventh chord on keyring
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Other Names:

Fully-Diminished Seventh

Symbols & Abbreviations:

°7, dim7



Set Class:


At times, this chord is simply a filled-out version of a diminished triad, and frequently serves the same transitional function. However, adding an extra minor third on top of the two existing minor thirds completes the symmetrical structure of this chord, as seen in the perfect diamond shape on the keyring. In this way, it’s now like the augmented triad in that it inverts back onto itself, which can result in a disorienting feeling. This helps make it the perfect material for sinister and shocking revelations, whether in Mozart’s Don Giovanni or to accompany the silent film trope of a dastardly villain with a damsel in distress.