I'm trying to go deeper into my study of chromatic harmony.

I was reading through the Tonal Harmony textbook, and it says that a "simultaneity" is "a chord for which a traditional Roman numeral label would be of secondary importance." The glossary says "the use of a traditional Roman numeral label is meaningless for such chords because the resulting tones do not function in the traditional sense."

When these chords come up in the book, they simply write out the actual letter for the chord instead of a Roman numeral.

However, when I looked up this term online, I didn't see anything come up related to the definition they provided.

Have any of you encountered different terminology for chords that are better explained without the use of Roman numerals? I don't know if other texts refer to this concept in a different way once they get to areas of deeper chromatic harmony.

Let me know any thoughts or knowledge you have about this; I'd appreciate it. Thanks in advance!

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    I can't say I'm familiar with the term. We had a question here that I remember being about a chord with every note of D harmonic minor in it; I imagine that's the kind of scenario you're talking about, where the idea of functional harmony starts to break down into voice-leading and clustery textures.
    – user45266
    Aug 30, 2019 at 5:09
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    I vaguely remember some weird chords where one triad was plonked on top of another, seemingly unrelated triad. I definitely remember this from a jazz improv class but maybe it also came up in a classical context. Sorry I don't remember more clearly. Aug 30, 2019 at 5:30
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    @aparente001 - That reminds me of the stacked chords brought up in a question on this website about "The Point of No Return" from Phantom of the Opera.
    – Dekkadeci
    Aug 30, 2019 at 7:10
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    @Dekkadeci - I'm not strong enough in theory to write an answer. Would you? Aug 30, 2019 at 22:03

2 Answers 2


Roman numerals are useful for describing music with a well-defined tonic. Once you start having to describe a chord as 'V7 of III of bVII' (and I've seen worse) it's time to just use chord names 'E7, Am6 etc.' And in today's music we can get out of that realm pretty quickly.

A 'simultaneity' as I understand it is a collection of notes that can't even be usefully named in this way without monstrosities like 'F♯m9add6sus2(omit root)' (and I've seen worse than that too!) The voices just lead to a combination of notes with no useful name, functional or descriptive. Stop looking for shortcuts, write the notes!

I don't think 'simultaneity' can be considered a standard term. If you want to use it in an essay or something, better explain it.

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    ‘V7 of III of bVII’ – I'd rather say this should be described as “V⁷ of Ⅱ”, or “Ⅴ⁷ of Ⅴ of Ⅴ” which is plausible enough. Aug 30, 2019 at 14:18

Roman numerals are just one of many notation conventions; to base definitions of harmony around how well they can be conveyed by roman numerals sounds, to me, like mistaking map for the territory. There is not one single overriding reason for which a chord might fall into the category of "not being described well by roman numerals", even the simplest triad can fall into this category if it appears in an atonal piece of music.

If such a word is necessary because you are specifically talking about notation, I'd probably just make up a word like "non-numerable".

I haven't read the textbook you're referring to, but it sounds like it might be hinting at non-functional harmony?

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