The en dash vs. the hyphen: examples for more precise English usage

You can tell there’s something wrong with me when I have a favorite punctuation mark. It’s the en dash, the bastard middle child between the hyphen and em dash, but it can provide oh-so-much clarity and eliminate oh-so-much ambiguity once you learn a couple simple rules for when it should replace the hyphen. The en dash has the HTML code –, the Unicode number 2013, and can be found, for example, in the Insert | Symbol | Special characters box in Microsoft Word. The Wikipedia article on the en dash, or “n dash” as it is sometimes written because it was originally supposed to be the width of a capital N (I guess “en” is the transcription of the word for the letter N), is very informative. I also wrote a tutorial on the proper uses of the en dash, based on the Wikipedia article and my experiences editing biomedical research manuscripts, on my Grammar page.

The en dash has multiple usages: to represent a range of numbers, to mean “and” or “to”, and to take the place of the hyphen when one side of the hyphen or the other (or both) contains a space or hyphen. This post is about the third use: When you would normally use a hyphen to create a compound adjective or some other compound term, but either side of the hyphenated phrase has multiple words or a hyphenated word, then the hyphen should be replaced with the en dash. A few simple examples of this replacement might make you think it’s no big deal and shouldn’t ever be bothered with:

stem cell–derived
Pulitzer Prize–winning
pro&#8211free market

Probably every time you have encountered those phrases and others like it, the hyphen was used instead, and it was clear enough. It wasn’t as precise as it could be, and we have a perfectly good punctuation mark to make those phrases as precise as possible, so if you’re going to use one almost-right punctuation mark, why not use the right one? It might not be the difference between the lightning bug and the lightning, but as the examples below show, there are times when the difference between the hyphen and en dash is almost that big, so it is better to follow the rule uniformly than to follow it sometimes and ignore it others (just like the Oxford comma!).

The main purpose of this post is to provide some example phrases in which the hyphen is completely unacceptable and the en dash is the only suitable punctuation mark:

non-current smokers vs. non–current smokers

This example is taken from a paper in which the authors divided their study population into two groups: those who were current smokers and those who were not. Therefore, their two groups were current smokers and non–current smokers. The only possible way to express this in a concise way and using the terminology that the authors wanted was to use the en dash. The hyphen isn’t just unclear; it is categorically incorrect. Non-current smokers with a hyphen means people who were smokers but aren’t currently, i.e., past smokers (or I guess future smokers too), which would specifically exclude never-smokers, which would have been incorrect according to the analysis these authors performed. Many similar examples can be imagined in which the “future” possibility really does apply, such as a prospective study that was conducted on people who weren’t smokers but became smokers later in the study, or weren’t diabetics but became diabetics, or weren’t pet owners but became pet owners, etc. Non-current with a hyphen is an adjective that applies to smokers, whereas non–current smokers is a single noun identifying a different, more inclusive group: people who no longer smoke and people who never smoked.

conventional extract–treated group

This group wasn’t an extract-treated group that received some other conventional treatment that earned them the “conventional” label; they were treated with the conventional extract (of green tea or something or other), which can only be expressed with the en dash and not with the hyphen.

FGF stimulation–dependent SHP2 activation

With a hyphen, this phrase would mean FGF activation of SHP2 that is stimulation-dependent. Dependent on what stimulation? It makes no sense. It is SHP2 activation that is FGF stimulation–dependent. The need for the en dash in this phrase does come partly from the stilted, super-formal conventions of scientific writing. This phrase appeared at the end of a sentence that could have been written, under different circumstances with a different meaning, as “…FGF’s SHP2 activation” (“FGF’s activation of SHP2”), but apostrophes are way too frowned upon in primary literature, so the awkward phrase “the FGF SHP2 activation” could be totally legitimate, if the FGF protein directly activated the SHP2 protein. It does not. Stimulation with FGF leads to activation of the intracellular protein SHP2, so with the multiple-word antecedent, the en dash is necessary.

postprandial TRL–mediated foam cell formation

Again, this is not TRL-mediated foam cell formation that is postprandial; it is foam cell formation that is mediated by postprandial TRL.

small RNA–dependent scaffold

This is an especially good example because “small” is a common adjective itself. This phrase means a scaffold that depends upon small RNAs as a necessary component, in contrast to a small scaffold that requires RNAs.

inter–stress fiber space

This is another good example of a prefix (“inter”) that needs to be followed by an en dash instead of a hyphen in this phrase. This means the space in between stress fibers, not an “inter-stress” fiber space, whatever that would mean.

All of my examples are from biomedical research papers because that’s the writing I encounter the most. What are some good examples that you’ve come across of the need to replace hyphens with en dashes?

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9 Responses to The en dash vs. the hyphen: examples for more precise English usage

  1. Pingback: The en dash vs. the hyphen: more examples for precise English usage | John Petrie’s LifeBlag

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  3. John Cowan says:

    Bah. These noun-noun pileups are simply not necessary and create nothing but confusion. The first one is neatly handled with current non-smokers. For the rest, clarity is generated not with en dashes, but by using more ordinary noun phrases: group treated with conventional extract, SHP2 activation dependent on FGF stimulation, foam cell formation mediated by postprandial TRL, scaffold dependent on small RNA, space between stress fibers. There is no rule against writing plain and clear English.

  4. John says:


    Your suggestion of “current non-smokers” is perfect and something I probably didn’t think of.

    Unfortunately, the rest of the “fixes” indicate your inexperience with primary biomedical literature and your lack of understanding of what most of those terms mean or how they would be used in a paper. One reason your fixes wouldn’t necessarily work so well all of the time is because the sentences these examples come from have other clauses that make it desirable to group these phrases into a single, compact noun phrase with as few prepositions and verbs as possible. In an already bulky sentence with multiple verbs and prepositions, changing “conventional extract–treated group” to “group treated with conventional extract” would almost certainly be more confusing and bulky, not less.

    Another good reason to group them together as nouns separated by en dashes is because they are treated as a specific, named location, molecule, or entity of some other kind that shouldn’t be stretched out with verbs and prepositions. For example, “inter–stress fiber space” was a location that the authors referred to a few times (maybe they abbreviated it “IFS” or “ISFS”, I don’t really remember), so it would just be too awkward and bulky to stretch it out into a longer phrase every time. “Small RNA–dependent scaffold” is the name of a specific type of molecule and definitely shouldn’t be stretched out or rearranged as you suggested, any more than you would rearrange “insulin-dependent diabetes” to “diabetes dependent on insulin”. I think in most sentences, you wouldn’t want to change “FGF stimulation–dependent SHP2 activation” to “SHP2 activation dependent on FGF stimulation” any more than you would change “glucose-stimulated insulin secretion” to “insulin secretion stimulated by glucose”. These are sort of standard, stock phrases, or at least phrases in a standard format, referring to phenomena or molecules or what have you in the most direct, concise way possible (most of the time) and should not be rearranged. In other words, it is often a matter of jargon, jargon that is not improved by your examples above. If you wrote “scaffold dependent on small RNA”, the reader would suspect you were not fluent in English or would wonder why you didn’t just write “small RNA-dependent scaffold” or “small-RNA-dependent scaffold” (the double-hyphen approach is certainly preferred by many language experts, such as Bryan Garner, I think).

    So please don’t come in here acting like you know more about writing for the biomedical sciences because you know a lot about clear writing in English or literature or linguistics or whatever. Sure, you can (and probably should) make the argument that most scientists are awful writers and most primary scientific literature is full of awkward, bulky indirectness and obscurity, but that doesn’t make my en dash examples undesirable or your fixes preferable.

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  6. Martyn Cornell says:

    I’m afraid your proposed solution to the problem is no solution at all. For a start, it assumes that people will automatically understand what you mean when you use an en dash as opposed to when you use a hyphen — which, of course, they won’t. Second, you assume people can easily distinguish between an en dash and a hyphen –which, of course, they can’t. YOU know what you mean, but others won’t.

  7. John says:

    “For a start, it assumes that people will automatically understand what you mean when you use an en dash as opposed to when you use a hyphen — which, of course, they won’t.”

    Some of them will. Which is why book publishers, scientific publishers, and others use the en dash. Is using a hyphen (or multiple hyphens) clearer?

    “Second, you assume people can easily distinguish between an en dash and a hyphen –which, of course, they can’t.”

    It is easy to distinguish between hyphens and en dashes in books, journal articles, and Microsoft Word documents, as long as the font is a good one.

  8. Jon Freed says:

    Should you have a hyphen between more and precise in your article title?

  9. John says:

    No. See: (As this source says, only hyphenate after “more” if it’s necessary to avoid confusion, which it wasn’t here) (This source is about “most” but its points apply to “more” as well; the reason they don’t mention “more” is because there are no absolute rules for “more” because it should be followed by a hyphen when context requires it, as mentioned in the previous source.) (CTRL+F “most popular”) (PDF) (Again “most” is mentioned but “more” isn’t because of the rare exceptions for “more”, which this post title isn’t an example of)

    And sorry for the extremely late reply. I clearly haven’t been taking care of my website very diligently lately.