The term refers to a specific note within a musical scale. It is the scale degree that lies immediately below the tonic, creating a strong sense of pull towards the resolution point. For example, in the key of C major, the note B acts in this capacity. This B naturally wants to resolve upwards to C, providing a satisfying conclusion to a musical phrase.
The note’s function is crucial in creating tonal harmony and melodic direction. Its characteristic upward resolution establishes a clear sense of key and provides a sense of closure. Historically, composers have used this tendency to build tension and release, shaping the emotional impact of their compositions. The strong gravitational pull of this note is fundamental to the structure of Western music.