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Music theory definition

Diminished seventh

A diminished triad plus a diminished 7th (°7) - four notes, all a minor 3rd apart.

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Play the example and listen for the idea described above.

Four-note chords

Add one more 3rd → .

Learn it in context

This term is introduced in Unit 11: Seventh chords. Work through the explanations and exercises to connect the definition with music.

Seventh chord
A triad with a fourth note a 7th above the root.
Dominant seventh
A major triad plus a minor 7th, like G7. It drives strongly to I.
Half-diminished seventh
A diminished triad plus a minor 7th (ø7), like Bø7.
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