5.4: Hyphens and Dashes

5.4.1: Hyphens

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Learning Objective

Identify situations which require a hyphen

Key Points

• Hyphens connect two words to make a single word. 
• Hyphens are also used to attach a prefix to a word.  
• In some situations, hyphens connect adverbs and adjectives to describe a noun. This can be avoided by rewording the sentence. 
• The placement of a hyphen can greatly change the meaning of a word and thus the entire sentence.

Key Terms

hyphen

The symbol “-“, typically used to join two or more words to form a new word.

homograph

A word that is spelled the same as another but has a different meaning and usually sounds different.

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. 

5.4.2: Em Dashes and En Dashes

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Learning Objective

Use em dashes and en dashes correctly in your writing

Key Points

• Dashes are commonly used to indicate an unexpected or emphatic pause, but they serve other specific functions as well.

• Dashes are often used to mark interruptions within sentences, illustrate relationships between words, and demarcate value ranges.
• There are two kinds of dashes: em dashes (—) and shorter en dashes (–).
• Dashes should not be confused with hyphens (-). 

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