Diminished triad
| Component intervals from root | |
|---|---|
| diminished fifth (tritone) | |
| minor third | |
| root | |
| Tuning | |
| 45:54:64; 54:45=6:5 & 64:45 | |
|
Forte no. / |
|
| 3-10 / |
In music, a diminished triad (
Play ), also known as the minor flatted fifth (m♭5), is a triad consisting of three minor thirds above the root — if built on C, a diminished triad would have a C, an E♭ and a G♭. It resembles a minor triad with a lowered (flattened) fifth. It can be represented by the integer notation {0, 3, 6}.
In the common practice period, the diminished triad is considered dissonant, or unstable, because the dissonant diminished fifth symmetrically divides the octave. The lack of tonal centre or stability, possession of a leading-tone, and the dominant function give the chord drive.
A diminished triad occurs in a major scale only on the seventh scale degree; in the key of C, this is a B diminished triad (B, D, F). Since the triad is built on the seventh scale degree, it is also called the leading-tone triad. The leading-tone triad also occurs in the seventh chord built on the fifth degree; in C, this is G dominant seventh (G, B, D, F). For this reason, it has dominant function. Unlike the dominant triad or dominant seventh, the leading-tone triad functions as a prolongational chord rather than a structural chord since the strong root motion by fifth is now absent.
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