First inversion in the context of "Dominant seventh chord"

In the music theory of harmony, the root is a specific note that names and typifies a given chord. Chords are often spoken about in terms of their root, their quality, and their extensions. When a chord is named without reference to quality, it is assumed to be major—for example, a "C chord" refers to a C major triad, containing the notes C, E, and G. In a given harmonic context, the root of a chord need not be in the bass position, as chords may be inverted while retaining the same name, and therefore the same root.

In tertian harmonic theory, wherein chords can be considered stacks of third intervals (e.g. in common practice tonality), the root of a chord is the note on which the subsequent thirds are stacked. For instance, the root of a triad such as E Minor is E, independently of the vertical order in which the three notes (E, G and B) are presented. A triad can be in three possible positions, a "root position" with the root in the bass (i.e., with the root as the lowest note, thus E, G, B or E, B, G from lowest to highest notes), a first inversion, e.g. G, B, E or G, E, B (i.e., with the note which is a third interval above the root, G, as the lowest note) and a second inversion, e.g. B, E, G or B, G, E, in which the note that is a fifth interval above the root (B) is the lowest note.

In music, the third factor of a chord is the note or pitch two scale degrees above the root or tonal center. When the third is the bass note, or lowest note, of the expressed triad, the chord is in first inversion.

The term sixth chord refers to two different kinds of chord, one in classical music and the other in modern popular music.

The original meaning of the term is a chord in first inversion, in other words with its third in the bass and its root a sixth above it. This is how the term is still used in classical music today, and in this sense it is called also a chord of the sixth.

In music, the supertonic is the second degree () of a diatonic scale, one whole step above the tonic. In the movable do solfège system, the supertonic note is sung as re.

The triad built on the supertonic note is called the supertonic chord. In Roman numeral analysis, the supertonic chord is typically symbolized by the Roman numeral "ii" in a major key, indicating that the chord is a minor chord (in C: D–F–A). In a minor key, it is indicated by "ii," indicating that the chord is a diminished chord (in C: D–F–A♭). Because it is a diminished chord, it usually appears in first inversion (ii) so that no note dissonates with the bass note.