Neapolitan chord
A major triad built on the lowered second scale degree, most often found in first inversion
In Depth
The Neapolitan chord, often notated as bII or N6, substitutes for the supertonic or subdominant in pre-dominant function. In first inversion its bass note is the fourth scale degree, which moves smoothly to the dominant. Despite its name, the chord was used across Europe well before the Neapolitan opera school adopted it. Its dark, poignant colour makes it especially effective in minor keys, where it introduces the lowered second degree as a chromatic visitor. Beethoven, Chopin, and Schubert all employed it as a hallmark of expressive harmonic writing.
The chord has nothing specifically to do with Naples — it was used widely across Baroque Europe before being associated with Neapolitan opera composers.