diminished

A diminished interval is one semitone smaller than a minor or perfect interval. The diminished fifth (tritone) — spanning six semitones — is the most important diminished interval, sitting at the exact midpoint of the octave and creating a distinctly tense, unstable sound that demands resolution. The diminished seventh chord stacks three minor thirds, creating a symmetrical structure that divides the octave into four equal parts. This symmetry means there are only three distinct diminished seventh chords — each one can resolve to four different keys, making it an incredibly versatile tool for modulation. Romantic composers like Chopin and Liszt used diminished chords extensively for dramatic effect.