Hyphens

Hyphens are often used to connect two words into a single term.

Hyphens (“-“) connect two words to make a single word. Though they look similar to dashes (“–” and “—”), they serve a different purpose. The dash is a form of punctuation that comes in between words whereas hyphens combine words. Like most components of English punctuation, hyphens have general rules regarding how they should be used. Hyphens are often used to connect adverbs and adjectives when describing a noun. Let’s explore these concepts in greater detail.

Linking Prefixes

Hyphens can be used to link prefixes such as non-, sub-, and super- to their main words. While it is possible (especially in American English) to attach these prefixes without hyphens, it is generally helpful to hyphenate when the letters brought into contact are the same. It’s also helpful when the letters are vowels, when a word is uncommon, or when the word could easily be misread. For example:

• Non-negotiable
• Sub-basement
• Pre-industrial

Units

In general, values and units are hyphenated when the unit is given as a whole word:

• 30-year-old man
• One half-dose

Homographs

Homographs are words that are spelled the same, but mean different things and may be pronounced differently. To prevent confusion, hyphens can be used to distinguish between homographs. For example:

• Re-dress (to dress again)
• Redress (to remedy or set right)

Combining Adverbs and Adjectives

Hyphens can be used to combine an adverb and adjective to describe a noun. In this situation, the adverb is describing the adjective, and the adjective is describing the noun. However, when the adverb ends with -ly, a hyphen should not be used.

• Disease-causing nutrition
• Beautiful-looking flowers
• A well-meaning gesture

It is not always necessary to use a hyphenated word. Sentences can be rearranged to avoid the need for a hyphen. If the adverb and adjective come after the noun being described, a hyphen is not needed. For example:

• A light-blue handbag sat on the bench.
• The handbag was light blue.

Remember that using hyphens to combine adverbs and adjectives in this way creates a new word. The placement of hyphens can greatly change the meaning of a word, thus changing the entire sentence. Let’s look at some examples of how removing a hyphen changes the meaning.

• Disease-causing poor nutrition. (Poor nutrition that causes disease.)
• Disease causing poor nutrition. (A disease that causes poor nutrition.)
• Little-celebrated paintings (Paintings that are underappreciated.)
• Little celebrated paintings (Small, appreciated paintings.)
• Government-monitoring program (A program that monitors the government.)
• Government monitoring program (A program the government monitors.)

Using hyphens correctly is important to clarifying these phrases.

Em Dashes and En Dashes

Dashes are often used to mark interruptions within sentences and show relationships between words.

Dashes

There are two kinds of dashes: em dashes (—) and shorter en dashes (–).

The Em Dash

Em dashes are often used to mark interruptions within sentences. They can be used with or without spacing.

For example:

• Three unlikely companions—a canary, an eagle, and a parrot—flew by my window in an odd flock. (Chicago Style)
• Three unlikely companions — a canary, an eagle and a parrot — flew by my window in an odd flock. (AP Style)

Em dashes are also used to indicate that a sentence is unfinished because the speaker has been interrupted. Similarly, they can be used in place of an ellipsis to illustrate an instance where a sentence is stopped short because the speaker is too emotional to continue.

For example:

• “Hey,” said Paul, “where do you think—”
• “I never understood why you—” Cesar trailed off.

Em dashes are sometimes used to summarize or define prior information in a sentence.

For example:

• When he saw his brother—his long-lost brother who disappeared six years prior—he broke down in tears. (Chicago Style)
• Today is St. Patrick’s Day — a day for family. (AP Style)

The En Dash

En dashes are used to demonstrate definite ranges of values. In these cases, there should not be any spaces around the en dash.

For example:

• June–July 1967
• 1:00–2:00 p.m.
• For ages 3–5
• pp. 38–55
• President Jimmy Carter (1977–1981)

The en dash can also be used to contrast values, or illustrate a relationship between two things. There are no spaces around the en dashes in these instances.

For example:

• Radical–Unionist coalition
• New York–London flight
• Mother–daughter relationship
• The Supreme Court voted 5–4 to uphold the decision
• The McCain–Feingold bill

An exception to the use of en dashes is made, however, when combined with an already hyphenated compound. In these cases, using an en dash is distracting. Use a hyphen instead.

For example:

• Non-English-speaking air traffic controllers
• Semi-labor-intensive industries

When he saw his brother—his long-lost brother who disappeared six years prior—he broke down in tears.: The title contains an example of em dash usage, which, in this case, shows a break in the sentence.