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The Half-Diminished Seventh

half-diminished seventh on keyring
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Other Names:

Minor Seven Flat Five

Symbols & Abbreviations:

ø7, mi7(b5)


Diatonic, Melodic Minor, Octatonic

Set Class:


This chord is most likely to turn up in a jazz context as part of a ii-V progression leading to a minor chord (e.g. iiø7-V7alt-i). The opening of “Stella By Starlight” is one example of this, although the melody extends the harmony beyond a seventh, as is often the case in jazz. Antonio Carlos Jobim’s “Corcovado” opens with this chord as part of a string of smoothly voice-led chords as is common in Bossa Nova. In a different inversion, this chord is a minor triad with a major sixth, heard sometimes in tango music and elsewhere. In the world of opera, this chord shocked German audiences in 1865 for its boldly-ambiguous appearance in the opening of Richard Wagner’s Tristan und Isolde. Called the “Tristan Chord” for generations onward, this chord in that context was recognized by many musicologists as being among the first signs of a shift toward atonality.