I have looked up online and studied usages for the hyphen, en dash, and em dash. I still haven't found an answer if I can define words with a dash in English.

The backstory on dashes defining vocabularies

I am bilingual in Russian and English. Back then when I was in a Russian school, we wrote dashes to introduce and define words in a notebook.

The following example is the usage of dashes to define words in grammatical Russian:

Gravity — the force that attracts a body toward the center of the earth, or toward any other physical body having mass.

Mass — a substance that has inertia and occupies physical space.

I did not know what type of dash they required but long enough to be em dash in handwriting was acceptable. Due to that, em dashes will be used in examples.

English equalities are "is." Russian also have equalities, but dashes are far more favorable and readable than ", it is."

All examples below mean the same in their respective language with English translation:

Russian: Mass — a substance that has inertia and occupies physical space.

Russian: Mass, it is a substance that has inertia and occupies physical space.

English: Mass is a substance that has inertia and occupies physical space.

The last line is, to my knowledge, the acceptable way of introducing and defining a word in English.

Question

Is it grammatical to use dashes to introduce and define a word?

Below is a clear, readable example of a short glossary:

Gravity — the force that attracts a body toward the center of the earth, or toward any other physical body having mass.

Mass — a substance that has inertia and occupies physical space.

Integrity — the quality of being honest and having strong moral principles; moral uprightness.

If an answer is: yes.

What type of dash should I use: hyphen, en dash or em dash?

If an answer is: no.

Are there any clear, readable alternatives for defining words while creating a glossary?

Gravity is the force that attracts a body toward the center of the earth, or toward any other physical body having mass.

Mass is a substance that has inertia and occupies physical space.

Integrity is the quality of being honest and having strong moral principles; moral uprightness.

Without dashes it's more difficult to differentiate between paragraphs and a glossary list. It's also more unreadable.

closed as primarily opinion-based by FumbleFingers, Knotell, JonMark Perry, J. Taylor, Scott Aug 14 at 6:27

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Just follow your chosen / designated style guide (or pick whichever orthographic convention you like best, if you're not constrained by a higher authority). Any advice given here would either involve Off Topic recommendations for specific styles guides, or be just people saying which versions they like best (essentially, "primarily opinion-based"). Plus to some extent this could be seen as a question about page layout / typesetting, which is hardly "Use of English" as addressed on this site. – FumbleFingers Aug 10 at 16:29
  • @FumbleFingers Perhaps the OP doesn’t have a “designated” style guide. If we answerers supply the OP with an answer taken from a style guide (such as the CMS or Garner’s), that answer won’t be “off-topic” or “primarily opinion-based”: it’ll be a stylistic answer which the OP can choose to heed or not. – user305707 Aug 10 at 16:34
  • @FumbleFingers Grammar and punctuation has everything to do with this site. The proper use of an em dash falls under the proper use of punctuation, and that is a very relevant topic on this site. – user305707 Aug 10 at 16:35
  • @TheWordsmith: I've never taken issue with questions such as Is the em dash used in formal writing? But this isn't that kind of question, imho. Your opinion may differ, of course, and you're perfectly entitled to hold it. – FumbleFingers Aug 10 at 17:05
  • @FumbleFingers Why isn’t this that type of question? – user305707 Aug 10 at 17:09
up vote 4 down vote accepted

What punctuation is used for glossary entries is completely a matter of style.

Although The Chicago Manual of Style (17th ed.) was referenced in different answers, its specific discussion of glossary entries was not.

From Chicago, 1.61 (emphasis mine):

A glossary is a useful tool in a book containing many words in another language or other unfamiliar terms. Words to be defined should be arranged in alphabetical order, each on a separate line and followed by its definition. (The term may be followed by a period, a colon, or an em dash, or distinguished from the definition typographically, or both.) A glossary usually precedes the notes and bibliography or reference list but may follow the notes, especially if terms listed in the glossary appear in the notes. A glossary that consists mainly of terms that do not appear in the text may be included as an appendix.

Also, in 2.23 (emphasis mine again):

Each entry in a glossary or list of abbreviations should begin on a new line, capitalized only if the term is capitalized in the text. Separate each term from the definition that follows with a period, a colon, or an em dash (choose one and use it consistently . . .). In a glossary, begin the definition with a capital letter, as if it were a new sentence; in a list of abbreviations, the expanded term should be capitalized or lowercased as it would be in text.

Chicago mentions only periods, colons, and em dashes. (And, in one section, the use of different typography, which I assume refers to such things as font face, emphasis, size, colour, and so on.)

Other style guides, as well as specific house style guides, may provide different guidance.

  • Thank you very much. The main idea of the post seems like that it's a style guide from "The Chicago Manual of Style 17th edition" rather than an actual English rule. – dmxt Aug 18 at 0:12
  • 1
    @dmxt There are no rules of style. You will never find a single, authoritative source that everybody uses. There are many different style guides, each of which that give their own guidance. Having said that, Chicago is the single most common style guide referred to. Second would be the Associated Press Style Book (and the first for anybody in journalism). Unless you are referencing some guide, then you are just expressing a personal opinion. Of course, you can do that. But it may not be something that's accepted by most people. – Jason Bassford Aug 18 at 2:32
  • To clarify, I originally posted this without knowing it's entirely opinions and styles in English, which I've never heard of before (I'm bilingual.) I was shocked that the trivial thing is so complicated that I can't even tell if it's acceptable to use em dash to define words in writings, such as in documentation, guides, articles, tweets, (heh) or YouTube comments. I don't even know what to use anymore, although "is" is probably the most correct grammatical, but I really like using (?)-dash for defining words, they split sections between paragraphs and glossaries beautifully. – dmxt Aug 18 at 3:56
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    Thank you for informing me that the Chicago Manual of Style is the most common style guide, I did not know this before this comment. So to my understanding, according to their style guide, using the em dash, as my example in the main post, is correct? And two more symbols, a period and a colon to replace em dash are also acceptable. – dmxt Aug 18 at 3:57
  • 1
    @dxmt Yes, that's exactly right. And your use of the em dash is fine in general. English can be confusing because there are often different ways of doing things—and, many times, large numbers of people will do things differently. A language like French, on the other hand, is controlled by a single ruling body. – Jason Bassford Aug 18 at 14:16

From the 17th edition of the Chicago Manual of Style:

An em dash is occasionally used to set off an introductory noun, or a series of nouns, from a pronoun that refers back to the noun or nouns and introduces the main clause.

Consensus—that was the will-o’-the-wisp he doggedly pursued.

Broken promises, petty rivalries, and false rumors—such were the obstacles she encountered.

So, to answer your question, yes you can use an em dash in this way, although note the word “occasionally.”

See this as well:

In British usage, an en dash (with space before and after) is usually preferred to the em dash as punctuation in running text, a practice that is followed by some non-British publications as well.

Some more incidental information (not necessary to read):

The em dash, often simply called the dash, is the most commonly used and most versatile of the dashes. (In British usage, spaced en dashes are used in place of em dashes.) Em dashes are used to set off an amplifying or explanatory element and in that sense can function as an alternative to parentheses (second and third examples), commas (fourth and fifth examples), or a colon (first example)—especially when an abrupt break in thought is called for.

It was a revival of the most potent image in modern democracy—the revolutionary idea.

The influence of three impressionists—Monet, Sisley, and Degas—is obvious in her work.

The chancellor—he had been awake half the night—came down in an angry mood.

She outlined the strategy—a strategy that would, she hoped, secure the peace.

My friends—that is, my former friends—ganged up on me.

To avoid confusion, the em dash should never be used within or immediately following another element set off by an em dash (or pair of em dashes). Use parentheses or commas instead.

The Whipplesworth conference—which had already been interrupted by three demonstrations (the last bordering on violence)—was adjourned promptly.

OR

The Whipplesworth conference—which had already been interrupted by three demonstrations, the last bordering on violence—was adjourned promptly.

(You can find these excerpts in the 17th edition of the CMS in the following locations: 6.86, 6.83, and 6.85 respectively.)

Let's start off by giving some broad rules:

  • A comma produces a break of some sort, whether it be a break so that what comes before it can be elaborated upon, a break to divide items in a serial list, or a break to introduce a quote.
  • An em dash produces a harder break than a comma. You may want this for literary effect, or you may need this because the item that comes after the em dash (or within a pair of em dashes) is reasonably long and requires prominence. Also, if the item has internal commas, an em dash helps to visually set off the whole piece.
  • An en dash is different than a comma or em dash. It is used to denote intervals, such as 6 - 12 eggs or 50 - 60 mph (I don't know how to insert an en dash in this text box, so imagine that that previous hyphen is an en dash.)

To introduce a single term, a hyphen usually suffices if you want the whole structure to be a grammatical sentence. For instance, contrast the following structures:

  • Gravity — the force that attracts a body toward the center of the earth, or toward any other physical body having mass.
  • Gravity — the force that attracts a body toward the center of the earth, or toward any other physical body having mass — is actually the weakest of the fundamental forces, and yet it shapes the macroscopic structure of the universe.
  • Gravity, the force that attracts a body toward the center of the earth, is actually the weakest of the fundamental forces and yet it shapes the macroscopic structure of the universe.

The first one uses a single em dash and is appropriate for a dictionary entry, but what results is not a grammatical sentence. The second one shows a pair of em dashes, and added text after that. The text between the em dashes describes and defines gravity, and it is appropriate to have em dashes set off that content because of the internal comma. In the third example, the material that had been between the em dashes is cut down so no internal comma is needed; now, instead of pair of em dashes setting off the text that defines gravity, we use a pair of commas. You probably could use an em dash in the last example if you really wanted to, but you don't need to, anymore. If the text that you want to set off is fairly long, you could use an em dash even if there are no internal commas, as in the examples that others have provided.

If all of this is confusing, consider this: as the material you need to set off becomes longer and more complicated, it becomes more and more desirable to use an em dash instead of a comma. An en dash is something else entirely, as previously described.

  • Thank you very much. May I ask if there is a source which determined this rule? – dmxt Aug 17 at 5:50
  • 1
    Check out the sources listed by Wordsmith in his answer. As for me, I find that it's a matter of feel and judgment. I have tried to ask a question very similar to yours and couldn't get any hard-and-fast rules like you can get when asking about subject/verb agreement. – JoshG Aug 17 at 15:30

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