Diminished octave

File:Diminished octave on C.png

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File:Diminished octave on C-sharp.png

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In music from Western culture, a diminished octave ({{errorTemplate:Main other|Audio file "Major seventh on C.mid" not found}}Template:Category handler) is an interval produced by narrowing a perfect octave by a chromatic semitone. As such, the two notes are denoted by the same letter but have different accidentals. For instance, the interval from C₄ to C₅ is a perfect octave, twelve semitones wide, and both the intervals from CTemplate:Music₄ to C₅ and from C₄ to CTemplate:Music₅ are diminished octaves, spanning eleven semitones. Being diminished, it is considered a dissonant interval.

The diminished octave is enharmonically equivalent to the major seventh.