What are Hyphens, En-Dashes, and Em-Dashes?

No doubt you’ve all heard of hyphens. They’re the little – that you find between some words, in phone numbers, and sometimes at the end of lines in old books, when it was necessary to break a word into two parts to make it fit. But what are the rules for using hyphens? And what on earth are en-dashes and em-dashes?

First, let’s look at the three together:

Hyphen –

En-Dash –

Em-Dash —

The hyphen is the shortest, the en-dash is slightly larger, and the em-dash is the largest of them all. Want to remember the difference between the en-dash and em-dash sizes? The en-dash and em-dash are named thusly because they are the width of the N and M in a font, respectively. (This is slightly less true now that we use proportionally-sized fonts almost exclusively, but an M is still wider than an N, just as an em-dash is wider than an en-dash.)

What are they used for?

The hyphen is most often used either to combine words, or when using compound modifiers. I’ll explain:

Combining Words

English is flexible, and English-speakers like to combine words that are frequently used together into what we call “portmanteau words.” Examples of such are words like labradoodle (labrador + poodle), bromance (brother + romance), and Medicaid (medicine + aid). Sometimes, however, words go through a transitional phase where they are hyphenated before becoming très chic portmanteau words. During that period, hyphens are used between the words to show that they’re joined and they must appear in that order to “make sense.” As they become more common, however, the words get “closer together” in our minds, and that hyphen is squished out in spelling. Go figure. In some ways, the hyphen acts like the apostrophe in a contraction, to show that something (in this case, a space) used to be there.

Compound Modifiers

A compound modifier is two words, used together in a set order, which modify (describe) another word.

Example:

She is a well-read woman.

In this instance, the two words are well and read, they only make sense in that order (well first, then read second), and they modify one word, woman.

Because they appear before the word they are modifying, they are hyphenated as a compound modifier.  If they came after the word they were modifying, they would not be hyphenated:

The woman is well read.

As an aside, compound modifiers which end in -ly or which contain proper adjectives or nouns are not hyphenated. You know, just to keep it fun. Thus, you would write, “The North American grey squirrel is an unmitigated pest,” and it would not be hyphenated.

Some prefixes also require hyphens

The prefixes pre-, post-, anti-, auto-, extra-, and re-, and so on can be used with or without a hyphen, as long as it makes sense either way. If one way or the other makes more sense, use it. However, the prefixes ex- and self- should always use hyphens. With ex-, just remember it as a way to distance yourself. You know, from your slimy ex-whatever.

Other rules:

If the prefix is before a proper noun, hyphenate it.

If the prefix ends in the same vowel as begins the word to which it is being joined, use a hyphen. Unless it’s an o, in which case you try it out and see how it looks. Yes, I know. I’m sorry. I didn’t do this, I’m just the messenger.

Other Places to Use Hyphens

Hyphens are also part of this punctuated breakfast when used in phone numbers, social security numbers, and in a tasty little number called the hanging hyphen, such as when we discuss things like “seventeenth- and eighteenth-century literature.” The hanging part is after seventeenth, of course, and it’s only hanging because it wants to get all compound with century like our bro eighteenth has there, but it’s too far away.

Use hyphens with ages

If the age comes before the thing that is that old and it is being used as an adjective or a noun, hyphenate it. Example: “The three-year-old dog refused to wear his boots.”

Age coming after the noun it is modifying? No hyphen. “The dog was three years old.” (Just like those compound modifiers up above, ya dig?)

Oh, and for reference, the AP guide removed the hyphen in email. It’s just email now. Don’t tell me to hyphenate it, because you can’t make me. Nyahh nyahh.

Okay, if hyphens are so handy, where do we use en-dashes and em-dashes?

En-dashes

En-dashes are connectors, and you can think of them as replacing the words to or through. They may be used to connect numbers in a range of numbers, such as those found in dates, or in page numbers.

Examples:

“Class, tonight, please read pages 120–168.”

“He lived from 1918–1978.”

There are also times when an en dash is used rather than a hyphen, but I’m going to be honest and say that those instances start getting a little cray-cray, and we don’t need to go there.

Em-dashes

What about em-dashes? Em-dashes are super-awesome things! You know how people use … all the time to make phrases stand out? That’s a great place to use an em-dash instead!

Example:

Incorrect: “I love em-dashes…and I’m not alone…because they are nifty.”

Correct: “I love em-dashes—and I’m not alone—because they are nifty.”

See how that worked? The em-dash can act as a stand-in for a comma or even a parenthesis when part of the sentence needs to be “set off” from the other parts. It’s like em-dashes are two arms for the center part of that sentence, holding the other parts from coming in and taking over and running over all that emphasis that the lover of em-dashes is not alone.

Don’t over-use em-dashes, but they really are handy. (Also, note that there are no spaces between the words and the em-dashes. Remember that when you use them.)

I hope this guide makes you a super-happy user of hyphens, en-dashes, and em-dashes—and that you’re able to use them without any self-doubt whatsoever, from 2015–onwards.