What does the term 'diminished' usually describe in music?

The term 'diminished' in music primarily refers to a reduction or decrease in something. In the context of harmony, a diminished chord consists of a stack of minor thirds, which creates a tension-filled and somewhat unstable sound compared to major and minor chords. This quality often conveys a sense of tension or unresolved harmony, suggesting a smaller or diminished interval between the notes involved.

To understand this more fully, when we consider the concept of making something "smaller," it aligns perfectly with the notion of creating diminished intervals — such as the diminished fifth, which is smaller than a perfect fifth, for example. This term aptly reflects the character of diminished chords and intervals, thus reinforcing the idea of reduction or minimization in musical context.