3-10

In music theory, a diminished triad (also known as the minor flatted fifth) is a triad consisting of two minor thirds above the root. It is a minor triad with a lowered (flattened) fifth. When using chord symbols, it may be indicated by the symbols "dim", "o", "m♭5", or "MI(♭5)". However, in most popular-music chord books, the symbol "dim" and "o" represents a diminished seventh chord (a four-tone chord), which in some modern jazz books and music theory books is represented by the "dim7" or "o7" symbols.
For example, the diminished triad built on C, written as Co, has pitches C–E♭–G♭:

The chord can be represented by the integer notation {0, 3, 6}.
In the common practice period, the diminished triad is considered dissonant because of the diminished fifth (or tritone).

View More On Wikipedia.org