Rootthirdfifthseventh

Rootthirdfifthseventh is a term used in music theory to describe the four essential chord tones that form many seventh chords in Western tonal music: the root, the third, the fifth, and the seventh. This sequence underpins the common practice of stacking thirds to build four-note chords and to spell their arpeggios.

Construction and quality: The root is the chord’s reference pitch. The third is either major or minor, influencing the chord’s overall mood. The fifth is typically perfect, though it can be diminished in certain chord types. The seventh, which can be major, minor, or diminished, determines the chord’s quality and its tendency toward resolution. Together, these four notes define several widely used seventh-chord qualities.

Common types (illustrated with C as the root): Cmaj7 uses C–E–G–B; C7 (dominant seventh) uses C–E–G–Bb; Cm7 uses C–Eb–G–Bb; CminMaj7 (C–Eb–G–B) represents a minor triad with a major seventh. Other variations include half-diminished sevenths (C–Eb–Gb–Bb) and diminished sevenths, which extend the same four-note idea with altered intervals.

Function and usage: In tonal harmony, the seventh adds tension that often resolves downward by step to the third of the following chord, a behavior especially characteristic of dominant sevenths resolving to the tonic. The root, third, and fifth provide the basic triad, while the seventh defines the chord’s harmonic function and potential resolutions.