First inversion

The first inversion of a chord is the voicing of a triad or seventh chord in which the third of the chord is the bass note and the root is a sixth (or corresponding compound interval) above it. In the first inversion of a C major triad, the bass note is E—the third of the triad—with the fifth and the root above it, forming the intervals of a minor third and a minor sixth (or corresponding compound intervals) above E, respectively.

In the first inversion of G dominant seventh chord, the bass note is B, the third of the chord.

In figured bass, a first-inversion triad is a chord (not to be confused with an added sixth chord), while a first-inversion seventh chord is a chord.

According to The American History and Encyclopedia of Music:

Note that any voicing above the bass is allowed. A first inversion chord must have the third chord factor in the bass, but it may have any arrangement of the root and fifth above that, including doubled notes, compound intervals, and omission (e.g., E–G–C, E–G–C–G', E–C'–G<nowiki></nowiki>, etc.)