Which term describes a long held note, usually in the bass?

The term that describes a long held note, usually in the bass, is known as a pedal point. A pedal point functions as a sustained note that is typically held in the bass while the harmonies above it change. This creates a strong tonal foundation and can evoke a sense of tension and release as the surrounding chords move. The use of a pedal point can enrich a piece's harmonic texture, contributing to the overall emotional impact of the music.

In contrast, ostinato refers to a recurring musical phrase or rhythmic pattern, usually in the melody or accompaniment rather than solely a bass note. A mordent involves a rapid alternation between a note and its immediate neighbor, adding embellishment rather than sustaining a single note. Lastly, an acciaccatura is a type of grace note that is played quickly before the main note, serving to ornament rather than sustain a tone. These distinctions illustrate why the term pedal point is the most accurate description of a long held note in this context.