I have troubles building compound adjectives and enumerating them. In my field (mechanics) we deal with forces which are proportional to displacement or velocity. We tend to call them "displacement proportional forces" and "velocity proportional forces". However, I have a feeling that a hyphen might be missing there: "displacement-proportional" and "velocity-proportional" seems to be "more correct" for me. Which of these two options would be the best?

Further, I would like to enumerate them like: "[...] featuring displacement- and velocity-proportional forces". But it just does not feel right. I have to admit, I have a German background and we do a lot of such shortening while enumerating - but does it work here as well?

  • English is a Germanic language and so we too can create compound labels like displacement- and velocity-proportional forces, where that dangling hyphen after displacement is a typographic signal that that word, too, should be connected to proportional. But I don't like it, no sirree bob. I'd much rather read forces proportional to displacement and forces proportional to velocity and forces proportional to displacement and velocity. – Tᴚoɯɐuo Nov 23 '18 at 16:38

What you're talking about is a suspended compound or a suspended hyphen. It's a stylistic choice, but it's perfectly acceptable according to the majority of grammarians:

From the Government of Canada's TERMIUM Plus:

When two or more compound adjectives contain the same word, to avoid repetition, writers usually omit that word from the compound(s) at the beginning of the series. Thus, first-class and second-class fares becomes simply first- and second-class fares, with the word class omitted in the first compound adjective.

Note that the hyphen before the omitted word is retained: first- and second-class fares (not first and second-class fares).

This structure is called a “suspended compound.” Here are some more examples:

      high- and low-pressure turbine
      interest- or revenue-producing schemes
      short- and long-term plans
      two-, four- and six-metre widths

From The Chicago Manual of Style (17th ed.), 7.88:

When the second part of a hyphenated expression is omitted, the suspended hyphen is retained, followed by a space (or, in a series, by a comma).

      fifteen- and twenty-year mortgages
      Chicago- or Milwaukee-bound passengers
      five-, ten-, and twenty-dollar bills

From Mignon Fogarty's blog post "How to Use a Hyphen":

You can also suspend hyphens. No, it doesn’t mean they got in trouble at grammar school, it means that to save space, you can suspend hyphens when you’re listing several words describing the same noun. How do you suspend them? Let’s say Santa found a fire-proof, dog-proof, and soot-proof vest online. You don’t need to write the full compound adjective each time, since each one is modifying the same noun, “vest.” Instead of writing “proof” each time, you’ll list them, each with only the first part of the compound, followed by a hyphen and then a comma. So if you were suspending hyphens when listing what type of vest Santa was planning on buying, you’d write that he purchased "the fire-, dog-, and soot-proof vest online."

Unless you are following a style guide that specifically gives different guidance, there is nothing wrong with using any of these presentations:

Velocity-proportional forces and displacement-proportional forces.
Velocity-proportional and displacement-proportional forces.
Velocity- and displacement-proportional forces.

You can also choose to rephrase it completely:

Forces that are proportional to velocity and displacement.

Which presentation you use is entirely up to you.

  • This is a really great answer with nice references and clear examples. I greatly appreciate your help. – Abyrwalg Naumov Nov 26 '18 at 8:59

Without knowing anything about your field, I would agree that those terms, individually, seem better with the hyphens:

velocity-proportional forces

displacement-proportional forces

In German, which I mention because you said you are German, I understand that you make a lot of compound words by joining them together. In a way, hyphenation is the English way of doing it, but we only normally link words that are related to each other. In your examples, the forces are proportional to either velocity or displacement, so it makes sense that they are "displacement-proportional" or "velocity-proportional". There is no need to join the word "forces" with a hyphen as well.

However, your other proposed sentence which attempts to abbreviate the use of both together is incorrect:

"... featuring displacement- and velocity-proportional forces"

You have included a hyphen at the end of the word "displacement" but it is not joined to anything! It should be fine to express this as:

"... featuring displacement and velocity-proportional forces"

It makes sense to me because the word "and" is joining "displacement" and "velocity", then the hyphen links them both to the word "proportional".

Consider this example:

I grew up with both London and Oxford-born friends.

It is fairly clear from context that you didn't grow up with someone called "London". It means you had friends born in both London and Oxford.

However, if you are concerned about any ambiguity in your specific context, it might be best to write:

"... featuring displacement-proportional and velocity-proportional forces"

  • 1
    I disagree with your "however". The longstanding (or long-standing!) convention is to include the hyphen with both conjunct components; without the first hyphen you are saying "displacement forces and velocity-proportional forces". – StoneyB Nov 23 '18 at 16:15
  • @StoneyB it depends on the context and the intended audience. I've added an example which proves my point, but I have also added that it may be safer to express it as you suggest. – Astralbee Nov 23 '18 at 16:18
  • @StoneyB thanks a lot for the extended answer and for the example. – Abyrwalg Naumov Nov 23 '18 at 17:30

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