What Is A Hyphen And How To Use It?

The hyphen, along with its cousins the en and em dash, may be the most misunderstood punctuation mark in English.

One reason that hyphenation is so complex: it changes over time. A tour through the Google nGram view of many common words reveals their hyphenated pasts: co-operate became cooperate, to morrow became to-morrow and then tomorrow, and good-bye became goodbye (though both are still acceptable).

So what exactly is a hyphen and what are all its uses? Let’s explore!

What is a hyphen?

A hyphen is “a short line (-) used to connect the parts of a compound word or the parts of a word divided for any purpose.”

To type a hyphen just use the key after the 0 on your keyboard. Easy!

When to use a hyphen?

Hyphens have very specific usages in the English language. Below we’ve outlined the most common usages with some examples.

To link numbers and ages

Age terms are another stumbling point for many. The hyphenation in the following two examples is appropriate: I have to babysit my three-year-old cousin. He has a five-year-old.

However, in the following sentence in which the age comes after (rather than before) the noun it modifies, no hyphenation is needed: Sheila is seven years old. One trick of the trade is to look for the plural of “years” in such constructions. If the word “years” is plural, chances are the construction does not need hyphenation.

When you write out a number in words, you should use hyphens to show a link between the number words (e.g. “There are ninetynine people invited.”)

To indicate line breaks

When the end of a line comes in the middle of a word, you can use a hyphen to divide it in a way it normally wouldn’t be.

It’s important to place the hyphen at a point in the word that won’t lead to confusion or misunderstandings. For instance, if the word dislocate needs to be split, the hyphen should come at a syllable break, becoming dis-locate.

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To create compound verbs and adjectives

The main function of hyphens in compound modifiers, or groups of words working together to modify a noun, is to eliminate ambiguity of meaning. For example, in the phrase “up-to-date technology,” we hyphenate “up-to-date” to signal that these three words are to be read as one concept, or adjective, functioning to modify the word “technology.”

One easy way to tell if you should use a hyphen is to pair each describing word on its own with the noun it’s describing. If the words don’t make sense without each other, you should hyphenate them. In the above example from 1984, the result would be prize physique and fighter’s physique. If the story took place in a modeling contest, prize physique might make sense, but this one doesn’t, so we need a hyphen to add clarity.

Hyphens are used to join parts of a word or compound phrase, as in ex-wife, full-length mirror, and by-the-book negotiations. As the Chicago Manual of Style puts it, “Far and away the most common spelling questions for writers and editors concern compound terms—whether to spell as two words, hyphenate, or close up as a single word.”

You can also use a hyphen to join two nouns, making a compound verb. Some examples of hyphenated compound verbs include ice-skate, window-shop, and air-condition.

Connecting prefixes

These days, most prefixes aren’t hyphenated, but it’s important to do when the meaning of a word is uncertain. For instance, when a hyphen is used in re-cover, the word means “to put a cover something again.” This helps avoid confusion with recover, which means “to get well.”

Hyphens are especially useful if the prefix ends in a vowel and the word being modified starts with a vowel. Some examples of this include co-own and co-opt.

How does a hyphen differ from an em or en dash?

These three dashes may look like they have a lot in common, but as you can probably guess, the em dash and the en dash have specific uses too!

Hyphen vs. en dash

En dashes are longer than a hyphen but shorter than an em dash.En dashes () can denote a range or connect the endpoints of a route. They can also show a contrast or connection between two words. It usually appears directly between the numbers or words it’s connecting, without spaces.

Hyphen vs. em dash

The em dash () sets off a word or clause and adds emphasis. Or, it can signal an interruption (see our article on interrupting sentences for more on that!) or amplification (“expanding”) of an idea. It’s also the longest of the dashes.