Neapolitan sixth

A Neapolitan sixth, one of the chromatic chords, is a chord constructed on the fourth degree of a diatonic scale with a minor third and a minor sixth above the bass. The Neapolitan sixth is the first inversion, and most common occurrence, of the Neapolitan chord, which is itself a major chord built on the lowered second (supertonic) scale degree. In the key of C it consists of F–A♭–D♭.