• A hyphen (-) is a punctuation mark that’s used to join words or parts of words. It’s not interchangeable with other types of dashes.
• Use a hyphen in a compound modifier when the modifier comes before the word it’s modifying.
• If you’re not sure whether a compound word has a hyphen or not, check your preferred dictionary.

 

Hyphen with Compound Modifiers: Multiple-Word Adjectives Before Nouns

Using hyphens to connect words is easy. Picking the right words to connect is a little harder. Let’s start with compound modifiers.

A compound modifier is made up of two or more words that work together to function like one adjective. When you connect words with the hyphen, you make it clear to readers that the words work together as a unit of meaning.

INCORRECT: It’s recommended you don’t take down any load-bearing walls when renovating.

In this sentence, it sounds like you shouldn’t take down any load that is holding up a wall. A hyphen should be inserted between load and bearing to make it clear that we’re talking about walls that are bearing a load.

CORRECT:

It’s recommended you don’t take down any load-bearing walls when renovating.

Generally, you need the hyphen only if the two or more words are functioning together as an adjective before the noun they’re describing. If the noun comes first, leave the hyphen out.

CORRECT:

This wall is load bearing.

You also don’t need a hyphen when your modifier is made up of an adverb and an adjective.

INCORRECT: Do you expect me to believe this clearly-impossible story?

Hyphens With Participles

Compound modifiers that include present or past participles follow the same rules as any other compound modifier.

Hyphen With a Noun, Adjective, Or Adverb and a Present Participle

When we combine a noun or adjective and a present participle (a word ending in ‑ing) to form a unit of meaning that describes another word, use a hyphen to make that unit of meaning clear.

INCORRECT: There are some beautiful-looking flowers in the garden.

Without the hyphen between beautiful and looking, your reader may stumble over the sentence. Perhaps there’s a new type of daisy called the “looking flower”?

EXAMPLES:

There are some beautiful-looking flowers in the garden.

Don’t use a hyphen when the modifier comes after the noun it’s describing.

EXAMPLES:

This medication is fast acting.

Don’t use a hyphen when you are combining an adverb and a participle.

INCORRECT: The room was like a heavily-decorated chocolate box.

The hyphen in a Compound Expression With a Noun and Past Participle

Compound modifiers that contain a past participle also follow the same rules as any other compound modifier. Use a hyphen when the compound goes before the noun it modifies:

The municipal government is funding a community-based education system.

Don’t use a hyphen when the compound comes after the noun it describes.

Hyphenated Compound Words

Hyphenated compound words are the ones (obviously) with a hyphen between the words. Over time, many hyphenated compounds become closed compounds—teen-ager became teenager for instance. Check a dictionary if you’re not sure whether to use a hyphen or not. Here are a few examples of common hyphenated compound words:

Mother-in-law

Closed Compound Words

Hyphenated words tend to become closed compounds (single words with no hyphens) over time. Email instead of e-mail, for example, is increasingly common. If you aren’t sure whether a word is a closed compound or a hyphenated one, check your preferred dictionary.

Notebook

Open Compound Words

Open compounds are typically made up of two nouns that are used together to represent a single idea. “Open” means that there is a space between the two words and no hyphen. A good dictionary is the best place to check whether a compound is open or not.

Living room

Hyphens and Numbers

Numbers between twenty-one and ninety-nine should be hyphenated when they’re spelled out.

Fifty-six bottles of pop on the wall, fifty-six bottles of pop…

Hyphen in Compound Adjective With Numbers

When numbers are used as the first part of a compound adjective, use a hyphen to connect them to the noun that follows them. This way, the reader knows that both words function like a unit to modify another noun. This applies whether the number is written in words or in digits.

The president of the company gave a 10-minute speech to the Board of Directors.

However, a hyphen is not required if the number is the second word in the compound adjective.

He is a victim of Type 2 diabetes.

Hyphen In Compound Adjective With Fractions

When using a fraction (e.g. half or quarter) as part of a compound adjective, it should be hyphenated so the reader understands which fraction is modifying which noun.

I half-wanted to commit a felony.

Hyphen With Prefixes: Ex-, Self-, All-

Use a hyphen with the prefix ex- (meaning former).

Don’t sit Adam next to Martha! She’s his ex-wife!

Use a hyphen with the reflexive prefix self-.

Lying on the floor beside the plant he had knocked over and chewed on, the cat looked extremely self-satisfied.

Make sure you don’t confuse the prefix self- with the noun self.

The self serves no other.

When using all as a prefix, add a hyphen.

It’s a bad leader who thinks of himself as all-powerful.

Hyphens with High or Low

When using high or low as part of a compound adjective, use a hyphen when the compound comes before the noun it’s modifying. Some examples of compound adjectives using high and low include high-level/low-level and high-impact/low-impact

Low-flying airplanes contribute to noise pollution in the area.