In music, the dominant is the fifth scale degree of the diatonic scale. It is called the dominant because it is next in importance to the first scale degree, the tonic. In the movable do solfège system, the dominant note is sung as "So(l)". The triad built on the dominant note is called the dominant chord. This chord is said to have dominant function, which means that it creates an instability that requires the tonic for resolution. Dominant triads, seventh chords, and ninth chords typically have dominant function. Leading-tone triads and seventh chords may also have dominant function.