Unfigured bass
Unfigured bass, less commonly known as under-figured bass, is a kind of musical notation used during the Baroque music era in Western Classical music (ca. 1600–1750) in which a basso continuo performer playing a chordal instrument (e.g., harpsichord, organ, or lute) improvises a chordal accompaniment from a notated bass line which lacks the guidance of figures indicating which harmonies should be played above the bass note (see figured bass).