What defines a seventh chord?

A seventh chord is characterized by including the root, third, fifth, and seventh degrees of a scale. This means that in addition to the foundational triad made up of the root, third, and fifth, a seventh chord adds an extra layer by incorporating the seventh note, which contributes to a more complex and fuller sound.

This seventh note can introduce various types of harmonies, such as major, minor, or dominant seventh chords, depending on the intervals between the notes. For example, in a major seventh chord, the seventh degree is a major seventh above the root, while in a dominant seventh chord, it is a minor seventh above the root.

Thus, the definition of a seventh chord highlights its distinctive quality, which is essential in various musical styles for creating tension, resolution, and emotional depth.