augmented sixth chord
A chromatic chord built on the flattened sixth scale degree containing an augmented sixth interval
In Depth
The augmented sixth chord appears in three standard forms: Italian (It+6), French (Fr+6), and German (Ger+6). All share the interval of an augmented sixth between the bass and upper voice, which resolves outward to an octave on the dominant. The Italian sixth contains only three notes, the French adds an augmented fourth above the bass, and the German adds a perfect fifth. These chords create intense chromatic tension that pulls powerfully toward the dominant, making them a favourite tool of Romantic-era composers for dramatic harmonic colour.
Mozart frequently used the German augmented sixth in his opera arias to heighten moments of emotional anguish.