inversion
Rearranging the notes of a chord so a note other than the root is in the bass.
In Depth
A chord inversion rearranges its notes so that a note other than the root is in the bass. A C major triad in root position has C in the bass; in first inversion, E is in the bass; in second inversion, G is in the bass. Each inversion gives the chord a different character and weight.
Inversions are essential for smooth voice leading — moving between chords with minimal movement in each voice. Without inversions, bass lines would jump erratically between chord roots. In figured bass, a notation system from the Baroque era, inversions are indicated by numbers below the bass note. Understanding inversions is fundamental to both composition and harmonic analysis.
The second inversion of a chord (like C/G) was considered so unstable in 18th-century theory that strict rules governed when and how it could be used. Breaking these rules was a mark of genius — or incompetence.