Is it correct to refer to modes as keys, or are they simply modes? If they're not keys, how come C Ionian is referred to as the major key, and its relative minor key, Am, (Aeolian), referred to as the minor key?

I've trawled through what folk will regard as dupes, but none seem to actually define what I'm after. 'A mode will use only the notes found in that mode' was one - doesn't sound particularly feasible.

Then we get the confusion between scales and keys. Scales are the notes of particular keys, played/written in an ordered fashion. Would that be a good description? If so, then Dorian, Phrygian et al will also have scales, thus notes belonging to certain keys.

Having read all the available q&a on the subject, I'd still like some defining facts, I'm sure I'm not the only one who's still confused. Or maybe I am..?

  • 1
    Are you looking for an exhaustive list of all different meanings for these words? There are many, many meanings. People use words like "mode", "scale" and "key", in different meanings in different situations. There is no single consistent definition, and there is no central language authority who defines what is correct. Commented Apr 28 at 13:23
  • @piiperiReinstateMonica - I am rather hoping there would be a 'proper' definition of each, and whether they are synonymous. The answers to similar questions seemed undecided, and ambiguous (including mine from a while ago).
    – Tim
    Commented Apr 28 at 13:41
  • How could there possibly be a "proper" definition of a word that only allows one single meaning, if the word is used in many different meanings, depending on person and situation? Any proper attempt at defining such a word has to take actual meanings into account. The purpose of words is communication, and the purpose of definitions is to understand what people mean with their communication attempts. Commented Apr 28 at 15:40
  • @piiperiReinstateMonica - I don't want this to be I say tomayto, you say tomarto situation. As a seasoned muso, I find it difficult to explain to students just what the different definitions of each word are. Hoping someone will be able to clear up 'well he says that, but I say that', as there should be a better defining than that. We have, in music, fairly well defined terms that are universally understood. These should (could) be likewise.
    – Tim
    Commented Apr 28 at 16:07
  • Tomayto and tomarto, different sounds but same meaning. Key, mode and scale, the words sound the same but meanings vary. When you teach these concepts to your students, it's good to settle on a specific meaning and stick to that consistently. If you've decided to go on a crusade and unify the usage of words and their meanings, well, that's an extremely unrealistic goal. Commented Apr 28 at 16:38

4 Answers 4


Modes and keys come from two completely different music theoretical systems. This does not hinder people in identifying these concepts. In the end this is a question of definition, which will differ depending on which music theoretical concept you are in. There is not even consense on how key, scale and tonal center relate. In classical theory key = scale + tonal center. In modern music key = tonal center. In pop music often key = major scale. Modes than get complicated. Modes naturally give birth to scales. These scales can be seen as alterations of minor/major scales, but can also be seen as defining a key.

Most commonly mode is used in the sense of a scale, usually applied melodically or harmonically to a major or minor key. But the most correct use (if you want to say so) comes from chant theory, and thus does not really link with concepts such as key or even scale (a mode does not define a scale, but things like the finalis and the cofinalis).


These terms are commonly used interchangeably, with the meaning clarified (hopefully) by context.

However, when I need to be very specific and distinct with their meanings, I think of them in this way:

  • Scale: I think of scales in the sense of "building to scale" — a set of measurements. The scale of a piano, for example, is the design of the string layout. So I think of a scale as something along the lines of "an ordered collection of ratios," say. The scale of a piano is chromatic; the scale of a (diatonic) harmonica is diatonic; and the scale of a 5-tone tongue drum is pentatonic.
  • Mode: Once a scale (a set of measurements) has been devised, a mode is the use of that scale centered around a particular pitch within it. A diatonic scale is a specific collection of measurements, which gives rise to seven modes.
  • Key: The idea of key comes from the theory of tonality. A key is a mode accompanied by a set of conventions about how that mode will be used. For example, aeolian modal writing would not use the leading tone; whereas, minor writing generally requires it. Key-based writing also privileges thirds and sixths and comes with rules about approaching and resolving dissonances — rules which don't (or needn't) apply in modal writing.
  • This is backwards, describing as it does the modern concept of mode, which is post-tonal, but placing it before the concept of tonality. The historical modal system did not have an Aeolian mode and did not avoid the leading tone.
    – phoog
    Commented May 3 at 1:37
  • @phoog Absolutely no chronology is implied by my post.
    – Aaron
    Commented May 3 at 2:38

Part of the problem is how these terms relate to music history.

Atcherson (1973) Journal of Music Theory - Key and Mode in Seventeenth Century Music is an article I read and thought does a good job of explaining the history. http://www.kholopov.ru/arc/atcherson.pdf

Mode, in the Medieval sense, the Church Modes, was based on the diatonic gamut and fixed finals (tonics) of D, E, F, G. The details of the system are not necessary here, but we can say each of those modes had particular intervallic structures, like the quality of their third, sixth, etc. scale degrees, but the modes did not transpose.

Keys developed after modes, and one of the important concepts that goes along with this system is transposition. The relationship between two keys like C and D major, for example starting on C4 and D4, is not just that D is higher, but that both keys are transpositions of each other.

From the Atcherson article I understand an early meaning of key was more like a selected pitch in a scale that could be tonicized.

Mode apparently took on the meaning of the intervallic relationships between pitches, which could be transposed to various pitch centers, and eventually became known as major and minor.

So, if I haven't misread Atcherson, the development over time involved changing tonal focus to different key tones, transposing pitch relationships to different tonal centers, and a reduction in a multitude of modal pitch relationships to only major and minor key relationships. Our modern sense of key bundles both ideas together, but the history was not so neatly defined. Now the modern sense is a key with two primary attributes: a tonic pitch letter and a mode of major or minor.

The modern use of mode in jazz differs from the Church Mode sense, because it treats modes as transposable like the major/minor key system. In the Medieval system dorian authentic was centered only on D. The modern concept can transposed that to any tonic/final, for example E dorian.

Another meaning of mode is rotation of a scale. Surely this comes from the modern sense that seven modes can be derived from a major scale. So, for example, D dorian is the second mode of C major. Then other more exotic scales are described that way, like lydian dominant is the fourth mode of the ascending melodic minor scale.

A scale is just playing all the tones of a tonality in ascending or descending pitch order.

Is it correct to refer to modes as keys,

For me, no. Tonalities is the common category I would use to lump modes and keys together. I understand your meaning, but it looses the history, and importantly the distinction between different tonalities. The devil's in the details. Phygian mode is like minor... except it really isn't a minor key.

...or are they simply modes? If they're not keys, how come C Ionian is referred to as the major key, and its relative minor key, Am, (Aeolian), referred to as the minor key?

That type of description comes from jazz teaching. Again, I understand the meaning, but I personally don't use those descriptions anymore. I suppose if you played in a key signature of zero sharps/flats, used some kind of modal harmony, rather than tonic/dominant major key harmony, calling the music C ionian would make sense.

I find it difficult to explain to students just what the different definitions of each word are. [from comments]

That should be in your OP!

Is this coming from the perspective of teach music based on the major/minor system of harmony? I assume it is.

  • Scale/mode/key are not interchangeable terms.
  • Mode has many meanings spanning centuries of music and styles.
  • Define what style is at play when discussing modes.
  • Understand it can take a lot of time and study to develop a good understanding.

Unless folks are prepared for a big digression into either Medieval music or jazz, or both, I would think it best to point out the deep history involved, and then give a nutshell review of tonal scale degrees and modal scale degrees, and that when you get to altering any tonal degrees you start to destabilize the sense of tonal music (or will just end up modulating keys.)


An attempt at definitions

I'm offering an answer not based on history, but how the terms "mode", "scale", and "key" are currently used (at least since the 20th century). In short, YES, the 3 terms have distinct and stable primary meanings consistent with other answers already submitted:

  1. Key has to do with tonal center of a musical segment. If the music is atonal, it's meaningless.

  2. Mode has to do with the "feeling evoked" by a collection of strategic notes being used in close proximity in that segment. By "strategic" is a combination of

    • melodic non-transitionary notes
    • essential notes of chords in primary beats, and
    • key notes in a cadence.

    So given a segment of music, we can usually say whether it is in the "major" / Ionian mode, "harmonic minor" / Aeolian #7 mode, Slendro Gamelan mode, various Middle Eastern modes, etc.

  3. Scale is a complete set of notes of a particular mode arranged in an ascending order starting with the tonal center. Because it's complete, it makes sense to analyze the music in terms of "scale degrees".

    A scale may not completely define a mode since if only certain notes in the scale are used, a different mode can be evoked (thus scale being a superset of notes in the mode). For example, a piece using only the notes in the C major scale can feel Aeolian, not Ionian, even if the piece starts and ends in C.

Answering your questions

Question: "Is it correct to refer to modes as keys, or are they simply modes? If they're not keys, how come C Ionian is referred to as the major key, and its relative minor key, Am, (Aeolian), referred to as the minor key?"

Answer: Although C major and A natural minor share the same notes, the strategic notes of a C major musical segment is different than an A natural minor. If one plays a segment from the middle of the music, we can immediately sense the "mode" although we may need to find the "key" near major cadences / the direction where the music converges toward. So, strictly speaking, when describing the mood of the piece we should use the term "mode", not "key".

Question: "A mode will use only the notes found in that mode" was one [answer. That] doesn't sound particularly feasible.

Answer: How about tweaking the definition: "A musical segment is called to be in a particular mode if the strategic notes only use the notes found in that mode."

Question: Scales are the notes of particular keys, played/written in an ordered fashion. Would that be a good description? If so, then Dorian, Phrygian et al will also have scales, thus notes belonging to certain keys.

Answer: Yes, a scale implies a key (as the starting note). But scale is artificial, theoretical analytical construct. The music dictates the mode (mood evoked) and the key (tonal center).

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