Seventh chords

Triads are three notes — root, third, fifth. Seventh chords are four notes — root, third, fifth, and seventh. You stack one more third on top of the triad.

Sevenths are everywhere in Greek music. Rebetiko progressions lean heavily on them, and laïkó songs frequently use them as the V chord pulling back to the tonic. Worth learning early.

The four common seventh chords

There are many possible sevenths in theory, but four cover almost everything you’ll play.

Name	Symbol	Formula	Example (root = C)
Major 7	maj7	root + M3 + P5 + M7	C – E – G – B
Minor 7	m7	root + m3 + P5 + m7	C – E♭ – G – B♭
Dominant 7	7	root + M3 + P5 + m7	C – E – G – B♭
Half-diminished	m7♭5 or ø	root + m3 + ♭5 + m7	C – E♭ – G♭ – B♭

Read the formulas vertically: every chord is the corresponding triad (major, minor, diminished) with a seventh — either major (M7) or minor (m7) — added on top.

The most important one: the dominant 7

The dominant 7 (just “7”) is the seventh chord you’ll meet most often. It’s a major triad with a minor seventh on top — that combination of bright triad plus dissonant top note gives it enormous forward momentum.

It got its name because it’s the chord built on the dominant (5th) degree of a key. In C Do major:

V7 = G – B – D – F

That F Fa is the minor seventh on top of the G Sol major triad. Played as a chord, it creates an unmistakable pull toward the tonic — the strongest “almost home” sound in Western music.

1. C
2. C#
3. D
4. D#
5. E
6. F
7. F#
8. G
9. G#
10. A
11. A#
12. B

Major 7 and minor 7

• Major 7 is a major triad with a major seventh on top — bright and jazzy. C Do maj7 (C-E-G-B) has a warm, lounge-music quality, less common in traditional rebetiko but used in modern Greek music.
• Minor 7 is a minor triad with a minor seventh. Smoother and less dramatic than a plain minor triad. The first chord of countless songs in every tradition.

These two are sometimes called “color” sevenths — they don’t pull you anywhere; they just add richness to the chord.

The half-diminished (m7♭5)

The half-diminished chord is a diminished triad with a minor seventh on top. The symbol ø shows up in some sources; on bouzouki tabs you’ll usually see m7♭5.

This is the chord built on the seventh degree of any major scale (the B° from chapter 2, now extended to a Bm7♭5 = B-D-F-A). It also appears as the ii chord in a minor key — and that ii-V-i progression with a half-diminished ii is a hallmark of jazz and adventurous Greek-pop harmony.

What about the fully diminished seventh?

There’s a fifth seventh chord called the diminished seventh (dim7 or °7) — a diminished triad with a doubly-flatted seventh. It’s a stack of three minor thirds.

In rebetiko it shows up frequently as a transitional chord between two main chords — a moment of intense dissonance that resolves immediately. We won’t cover its construction in detail here; once you know how diminished triads work, the diminished seventh is just “add a minor third on top of the diminished triad.”

Pattern memory aid

Triad	+ Major 7 =	+ Minor 7 =
Major	maj7	dominant 7
Minor	(rare)	m7
Diminished	(rare)	m7♭5

The combination of triad quality + seventh quality describes any seventh chord you’ll encounter. Master the four common ones above and you have 90% of the chord vocabulary you’ll need.

Recap

• A seventh chord is a triad plus one more third stacked on top.
• The four common sevenths are maj7, m7, dominant 7 (“7”), and m7♭5.
• The dominant 7 is a major triad + minor seventh and creates the strongest pull toward the tonic in Western harmony.
• The Am – E7 – Am-style cadence is the bedrock of rebetiko minor-key progressions.