What is a Hyphen?

Hyphens are used to form a compound word. A compound word is the joining of two separate words to form one concept. Hyphens should be used when there is a compound adjective directly before the noun that it describes. There are other times in which a hyphen is needed such as brother-in-law or other family members that follow that example. Many two-digit numbers also require the use of a hyphen, such as twenty-four. Any words including self or ex should also be hyphenated.

“Susan glared at the cloud-filled sky as she half-heartedly trudged along the pedestrian-filled walkway in search of a noise-free area in which she could finish her much-dreaded homework.” That sentence may sound a little long and clunky, but if you write it out, you’ll see that it’s filled with words that are hyphenated. Today, we’ll be looking at exactly what a hyphen is, and when we should and shouldn’t use it in our writing.

Let’s begin with two basic ground rules that are often broken.

1) Hyphens should not be confused with dashes:

Note that the hyphen is a single, short line, while the dash is longer. Dashes are also used differently, but we’ll leave that for another video.

2) Avoid spaces between hyphens and the text they are connected to. For example, in the word self-esteem, there is no space between the word self and the hyphen or between the hyphen and the word esteem.

Correct: self-esteem
Incorrect: self – esteem

Keeping these two rules in mind will save you a lot of trouble moving forward.

Now let’s look at some more hyphen rules.


Rue number 1: compound adjectives

When multiple words come together to form a single idea that modifies a noun, which we call a compound adjective, then hyphens should be used between each word. Examples include well-lit room, state-of-the-art technology, and fur-covered animal.


Rule number 2: creating original compound verbs

Sometimes we create original, creative verbs in our writing. Using hyphens to connect these words reduces ambiguity and shows that the two or more words should be read together as a single verb. For example:

“The slacker video-gamed his way through life.”

Note here that video-gamed is not an established verb, but the writer has used it as a way to creatively express the way in which the slacker went about his life. Since it is a made-up verb, a hyphen is required in order to show that it is a verb and to prevent confusion.1


Rule number 3: creating new or unusual compound nouns

As with verbs, we can also create nouns using two or more words. When these compound nouns are not already established and widely used, it is best to use hyphens between the words in order to prevent confusion. For example:

“I changed my diet and became a no-meater.”

Here, the hyphen is important because “no meater” without the hyphen might be confusing. Including the hyphen tells readers that no-meater is a single concept.


Rule number 4: avoid hyphenating between very and adverbs ending in –ly

It may seem correct at first glance, but avoid hyphenating between very or an –ly adverb and the noun or verb being modified. For example, you wouldn’t use a hyphen when describing a very tall man, nor would you use one to describe a finely dressed man.

However, do keep in mind that the –ly rule we’re talking about only applies to adverbs (words that modify a verb). Not all words ending in –ly are adverbs and they can often be used to create compound adjectives like those discussed in Rule 1. For instance, the word family ends in -ly, but since it isn’t an adverb, you would put a hyphen when using it to describe something like a family-owned restaurant.


Rule number 5: hyphenating to tell age

Use hyphens when writing ages that include the words year, month, day, or week. For example, if your dog is two years old, you would use hyphens to describe him as a two-year-old dog.

I have a two-year-old dog.

However, if the time period is plural, you do not use a hyphen. If you were describing the age of your kitten that is six weeks old, there would be no hyphen between six and weeks.

My kitten is six weeks old.


Rule number 6: hyphenating spans or estimates of time

Hyphens should be used either between a span of time or an estimated range. For example, 1996-2007, 50-60 people, and 12:00-3:00 are all hyphenated.


Rule number 7: compound numbers from twenty-one to ninety-nine

This rule is mostly self-explanatory. Always include a hyphen when writing out numbers between 21 and 99 in word form.

  • Twenty-six
  • Thirty-five
  • Sixty-fourth
  • Ninety-first


Rule number 8: ex-, all-, self- prefixes

Use a hyphen after the prefixes ex-, all-, or self-. For example, ex-wife, all-knowing, and self-esteem are hyphenated.

All of these examples we’ve looked at are not an exhaustive list of all of the rules for hyphenating, but they are the main rules that are most important to remember. Here is a quick rundown of some other rules to make note of:

First, hyphens can be used to reduce ambiguity in writing. For example, recover vs. re-cover. Recover means to get better, but re-cover means to cover up something that was previously covered.

Second, spelled-out fractions should be hyphenated. For example: Two-thirds, nine-fifths, and one-fourth.

Third, hyphenate double last names: For example: William Smith-Jacobson.

Fourth, hyphenate prefixes for proper nouns and adjectives. For example: mid-September or trans-Pacific.

Fifth, hyphenate family relations that use the word great, such as great-aunt or great-great-grandmother.

Sixth, when combining two or more hyphenated words or phrases, keep the hyphen after the last word before the conjunction, such as two-year- to three-year-olds or eighteenth- and nineteenth-century art.

As you can see, there are a lot of rules for using hyphens. If you’re ever unsure if you should use a hyphen when you’re writing, a dictionary is a great resource to use.

Before we go, let’s look at a review question to see what you remember.
Which of the following is false?

  1. Hyphens should be used when self- is a prefix
  2. Hyphens should be used in compound adjectives
  3. Hyphens should be used after adverbs ending in –ly
  4. Hyphens should be used when spelling out numbers between 21 and 99

The correct answer is C. Remember, avoid hyphenating between an -ly adverb and the word it’s modifying, as well as the word very.

I hope this review was helpful! Thanks for watching, and happy studying!



by Mometrix Test Preparation | Last Updated: January 14, 2021