In music, the dominant is the fifth degree of the scale. For example, in the C major scale (white keys on a piano), the dominant is the note G; and the dominant chord uses the notes G, B, and D. In music theory, the dominant chord is symbolized with the Roman numeral V if major and v if minor.

A cadential dominant chord followed by a tonic chord (the chord of the key of the piece) produces an authentic cadence. If the rootss are in the bass and the tonic is in the highest voice, it is a perfect authentic cadence.

"Dominant" also refers to a relationship of musical keys. For example, relative to the key of C major, the key of G major is the dominant. Music which modulates (changes key) often modulates into the dominant. Modulation into the dominant key often creates a sense of increased tension; as opposed to modulation into subdominant (fourth note of the scale), which creates a sense of musical relaxation.

See also: Dominant seventh chord