I have this strange thought over which I argue with people. If a chord is a set of distinct tones sounding simultaneously (or one after another like in arpeggios) then for instance a root C in the bass together with a few more C's on other octaves should also be called a chord. For instance we have four notes which are C on the piano in different octaves - they are all distinct tones. Not the same note in terms of hertz and position (unlike on the guitar where we can have two or more same notes in an octave but they would sound different). Yet, in musical theory the most simple chord should consist of a root, a third, and a fifth. However, a two note chord with only the root and the fifth is called a power chord (C5 for instance), but we don't have a chord for only the root and the third, whether it be the minor or the major third. But then how do we identify the chord if it does not have a minor or a major third?

So in terms of piano keys what is a chord?

  • 1
    A chord is essentially notes which produce harmony together. Can't hear any harmony in a number of different octave C notes played together. Power chord may well be a misnomer.
    – Tim
    Commented Jun 14, 2020 at 6:46
  • @piiperiReinstateMonica Described in the question, reedited! Commented Jun 14, 2020 at 7:58
  • @SovereignSun Just for fun, on any physical instrument a single note has already harmonic information, given by its overtone series, which includes the octave, perfect fifth, etc. This is in part what allows us to identify the very specific signature of a tone on each instrument, so its definitely information our brain percieves. Would you call a single note a chord based on this?
    – hirschme
    Commented Jun 14, 2020 at 19:13
  • @hirschme Probably, if the harmony says so. Commented Jun 15, 2020 at 4:05

6 Answers 6


what is a chord?

In other words, what does a chord do. If you encounter something that doesn't do those things, then you shouldn't call it a chord in that sense. (The "is" word is called a copula https://en.wikipedia.org/wiki/Copula_(linguistics) and your question is basically a general request for explanations about the problem domain where the word "chord" is used - and the answers better be focused around sentences about doing, not other copulas)

What does a chord do?

Chords explicate, bring out several features about the harmonic context at the same time. Chords are capable of explicating more features per time unit than a single-voice melody line, so they have more harmonic expressive power. Chords are harmonic bulldozers compared to single-note shovels.

When you listen to music, your ear constantly tries to keep track of a few important things:

  • (1) what is the home note, i.e. tonic. That's the home position.
  • (2) what is the expected harmony, i.e. set of intervals around the home note. This is the home shape.
  • (3) are we at home now, i.e. is the harmonic position and shape of the set of currently sounding notes sitting on the tonic and in the home shape, or is it away from the tonic in some way, or in a non-home shape.

The harmonic context around the tonic is defined in a space of one single octave. A single note, say, C, can only explicate "C". It doesn't say which octave, because there are no octaves in the harmonic context. The set of octaves and that kind of spacing has more to do with timbre than harmony. If you have a chord C, E, G, you can voice it in many ways by spreading the notes in different octaves, and it will create a different sound, but harmonically it still only does the same thing any C major triad does. It says three things: (1) there is a C, (2) there is an E, and (3) there is a G. (plus, the lowest note is an extra feature, but IMO that's not relevant for the chord vs non-chord question)

When you have one or two or three or a thousand different sounding C notes, even the whole mass of them only says "there is a C", that's all. That's a very weak harmonic device! Definitely not a bulldozer. The so-called "power chord" is actually a weak harmonic device, not harmonically powerful at all. It is powerful in terms of timbre and for putting more weight to its root note.

If you hear an F major chord as the set of currently sounding notes, but in your mind you've established C major as the tonic position and shape, then you feel that you're not at home. You want to hear a C major to make yourself feel that you returned home. Or at least a plain C note that leaves room for imagining the C major around it. If you only hear a single F note, it doesn't leave room for imagining this - you are not at home with any stretch of imagination ... unless you keep playing the F note for so long that in your mind you move your bed and fridge there. This usually happens in about a minute.

"Is this a ... "

Language is always used in a context. What is your context? When is it justifiable to call something a chord? Will doing that labeling be good or bad for your intentions?

Is this a chord? Is it major, minor or suspended? Cluster chord? If you heard that played, would you say you heard a chord? Did you hear one pitch or multiple pitches? Regardless of instrument? If you sample this, can you play melodies with it? Can you play other chords with it?

Is this a chord?

How about this one, is it a chord?

Is this a chord?

Is the following a chord? The two half-notes in the first bar are most definitely chords, but would you say it ends on a non-chord?

Is this a chord?

Consider your context and make up your own mind. :)

  • So is it or is it not a chord? Commented Jun 14, 2020 at 19:04
  • @SovereignSun if you can't tell from reading this answer, then I can't help. Sorry. Maximal effort has been given. Commented Jun 14, 2020 at 19:09
  • I can, but you didn't give the straight answer, which I would appreciate if you did. Commented Jun 15, 2020 at 4:07
  • What if you take sound synthesised sound that dropped out of normal notation and has polyphony, won't one key make a chord then? Commented Jun 15, 2020 at 4:14
  • 1
    @SovereignSun As piiperi wrote, you should ask whether it functions as a chord, not whether it is a chord. The latter just becomes a question about definitions, which isn't useful in itself.
    – Ian Goldby
    Commented Jun 15, 2020 at 15:27

The standard concept of chords is stacked thirds. That is, given a scale, start at some point and take every third note.

For example, given the scale C D E F G A C etc. you take C E G, D F A, etc.

If you take three notes in this way, the chords are called triads.

If you take 4 notes at a time, they are called "seventh" chords, e.g. C E G B, D F A C, etc.

Now, in case of power chords, you are already stretching the concept to some extent, and indeed some theorists would say that two notes do not a chord make.

In case of a two-note chord made of a root and a third, personally, I would still call it a major or minor chord. Indeed, removing the fifth from a chord is less extreme than removing the third. In other words, to my mind and to my ear, C-E (C major without a fifth) sounds more like a chord than C-G (C5 or C power chord).

But when you take it to the extreme of having just one note, even if at different octaves, I think that's stretching the concept of chord one step too far -- you've just got one note.

  • To ponder upon - play notes E and G. Now, are they root and m3 of Em, or M3 and 5 of C major, or 5 and m7 of A7..?
    – Tim
    Commented Jun 14, 2020 at 6:54
  • @Tim Which comes first, the E or the G? Commented Jun 14, 2020 at 7:12
  • @Tim If there's nothing else going on, I definitely hear E and G as an Em, especially if the E and G are near each other. I find that any m3/M3 interval alone is already extremely suggestive of the corresponding chord with the lower note as the root. Of course, that depends on my Western musical background, but then again, the fact that we (Western world) ended up naming chords and scales primarily based on this m3/M3 interval is not completely arbitrary or accidental -- there is quite a strong natural and instinctive attracting force in them. How do you feel it?
    – MMazzon
    Commented Jun 14, 2020 at 7:13
  • I tend to hear it as A7. But when it's G under, close position, it becomes a C major. Probably hearing the lower note as a root is part of our conditioning - as a bassist it's part of my remit..!
    – Tim
    Commented Jun 14, 2020 at 7:21
  • 3
    Stacked thirds are not “the” standard concept to chords, they are one approach to how to construct chords by default, which is standard in some genres. Commented Jun 14, 2020 at 8:53

There are various definitions of 'chord'. Some say two distinct tones are sufficient. Some insist on a minimum of three. But there's general agreement that 'distinct tones' means 'distinct pitch classes'. The same note in another octave counts as one.

Now, is ANY group of tones a 'chord'? Is it still a chord if it can't usefully be given a name?

Is the dyad C,E sufficient to be defined as C major? (Remember Harmony 101 where we're taught that in Bach-style 4-part writing 'the 5th may be omitted'?)

What about the 'power chord' C,G ? We've latterly given it a name, 'C5'. We can count that as a chord, can't we?

How about a cluster. C, C♯,D, D♯ ? Probably pointless to attempt naming it, but is it a 'chord'?

We're now in the territory of 'Topic For Discussion' rather than 'Question With a Definite Answer'.

  • 1
    A cluster is definitely a chord for me, take C, D, E, F for instance. That could be anything, but it's a chord, and even two notes appart like C, G# is a chord, we just don't know what chord it is. It could be anything either. Commented Jun 15, 2020 at 4:11

It's definitely a chord, though it is very poor in harmonic information.

It does not provide any definitive clue on the tonality or the role inside the tonality, etc.

However, as it very strongly sets the note that it is stacking up, chances are high that it is the tonic (1st note of the tonality, e.g. C in C Major). Or maybe, next likely, the dominant (5th note, e.g. G in C Major).

  • 2
    Practically every instrument's sound has harmonic overtones, which means that pitches are sounding in many octaves. So, any note played on any instrument is a chord? Commented Jun 14, 2020 at 19:14
  • No, a chord is a concept stemming from polyphony, or the fact that the player is uttering several notes at the same time. The concept of note itself is related to the atomic event producing the simplest sound on the instrument. So for example, on a viola d'amore, even if each time a string is excited it makes resonate the corresponding sympathetic string, it is still only one note.
    – Almeo Maus
    Commented Jun 14, 2020 at 23:24
  • Note, chord, are concepts completely linked to music execution, the succession of actions made by the player. They are not directly linked to the result, to the physical nature of the sound produced. A chord means playing several notes at the same time.
    – Almeo Maus
    Commented Jun 15, 2020 at 1:19
  • @piiperiReinstateMonica Not one sound. Commented Jun 15, 2020 at 4:13
  • So, In key C major, ending someting with several octaves of B notes, what chord will that B be?
    – Tim
    Commented Jun 15, 2020 at 5:27

Depends on context.

The conductor of a symphony orchestra, during rehearsal, would probably refer to that as unison doubled at the octave.

A music theory student would be chastised for calling it a chord. A chord must have three or more notes, by definition. However, it could be called an implied chord if the context justified it.

An atonal composer would refer to it as a simultaneity composed of a several pitches but only one pitch class.

A musician in a rock band trying to teach his group a song would probably not refer to it as a chord as that wouldn't really accurately tell them what to play. They would probably call it a note," e.g. a "A major chord, then E minor chord, then a C note."

A guitarist might call it a partial chord.

A computer programmer writing, say, an Ableton plugin, might call it a special case of a chord, and it would be reasonable for a chord generator to allow for chords composer only of a single note at various octaves.


In mathematics, basically everything has an identity operator that changes nothing. For instance, x + 0 = x and y * 1 = y. So, even when you add zero, nothing changes but it still counts as addition and when you multiply by one nothing changes but it is still multiplication.

If you look at it that way, the unison chord is the identity operator of the chord construction operation. You add no extra harmonics to the root note, but you could still see it as a chord.

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