The hyphen: a household staple
The hyphen is the duct tape of punctuation—a household staple with many uses. This common symbol is encountered every day in telephone numbers, ISBN numbers, and other strings of digits. It is sometimes located at the end of lines to indicate word breaks. The hyphen can also be found squished between words or parts of words, joining them to express a single idea. And, by linking certain words, the hyphen separates others—preventing confusion or ambiguity (small bird sanctuary versus small-bird sanctuary).
Let’s take a look at when hyphens should be used and how.
Using hyphens as separators
Hyphens are used to separate letters when a word is spelled out letter by letter, as in:
- Dialogue (My name is spelled b-r-e-t-t.)
- American Sign Language (I just learned how to fingerspell b-r-e-t-t.)
Hyphens also separate numbers that are not inclusive, breaking up long strings of digits into chunks that are easier to remember.
- Telephone numbers (1-800-325-5678)
- ISBN numbers (978-3-16-148410-0)
Using hyphens to show end-of-line word breaks
Hyphens are used to show breaks—where a word is divided at the end of a line of text. These hyphens are called soft, because they disappear if the word falls on one line. Writers and editors rarely need to worry about soft hyphens; most word processing programs bump a word to the next line if there isn’t space. And, even when breaks appear in a manuscript, they will likely differ from the proofs—which are in the hands of the typesetter and proofreader.
If you do edit a manuscript with breaks, mark all soft hyphens with a “close-up and delete” sign. This tells the typesetter to lose the hyphen if the word is moved to one line.
If you are a proofreader, soft hyphens are in your domain. Here are some guidelines:
- Breaks usually occur between syllables. Words in the dictionary show dots or hyphens where a word may be divided (di · vi · ded). Dictionaries sometimes differ, however, in how they separate words into syllables—always consult the house dictionary to ensure consistency.
- Never break a URL with a hyphen. If a hyphen is part of the URL, do not let it appear at the end of a line. The Chicago Manual of Style provides guidelines on how to break up long URLs.
Read more on end-of-line word breaks.
Using hyphens to join compound words
A compound word is a combination of two or more words used together to convey a new meaning. There are three types of compounds: open (rat race), closed (sunset), and hyphenated (in-depth).
New compound words are often open or hyphenated. The hyphen serves as a temporary bond until the words are either fused together (e-mail is now email) or split into open compounds (ice-cream is now ice cream). Sometimes, however, the hyphen sticks (mother-in-law). Always consult your house dictionary. If the word isn’t listed, follow these general guidelines:
- Adverbs ending in –ly are not followed by a hyphen (highly intelligent).
- Combining forms are closed if permanent, hyphenated if temporary (agro-social).
- Compound nouns are usually open (voice box), but there are exceptions (voice-over).
- Compound single-word verbs are sometimes hyphenated (hand-feed), sometimes closed (breastfeed).
- Compound adjectives are hyphenated before a noun—not after (ten-story building).
These guidelines just scratch the surface, and they all come with exceptions. Read more on hyphenating compound words.
Using hyphens to join prefixes to words
Words formed with prefixes are normally closed, but hyphens should be used in a few situations:
- Before a numeral (post-2000)
- Before a hyphenated compound word (non-English-speaking)
- Before a proper noun or adjective (anti-Trump, pre-Columbian)
- Between identical letters or syllables (anti-immigrant, de-emphasize)
- In a word that would otherwise be misread (re-cover)
- Between repeated terms in a double prefix (sub-subsidiary, co-coordinator)
Note: When placing a prefix before an open compound (post–World War II), the en dash is used.
Using hyphens to indicate a missing or implied element
A suspended hyphen is used when a hyphenated expression has multiple adjectives sharing the same last word. Delete all the repeated words except for the last one, but keep the hyphens to indicate the common element. Leave a space after the suspended hyphen.
- Ottawa- or Quebec-bound passengers
- One-, three-, and five-year-old children
The same rule applies to a solid compound.
- over- and underweight patients
Leave out the space when describing a single entity (a sixteen-by-twenty-inch canvas) or a single range (a twenty-to-thirty-minute drive).
Using hyphens to spell out numbers
When spelling out numbers, use a hyphen to join two-digit numbers between twenty-one and ninety-nine.
- thirty-nine thousand, thirty-nine million, nineteen thirty-nine
The hyphen: a short line with a long list of uses
For such a humble little line, the hyphen is virtually indispensable. But, with every use, there’s another rule to remember—and an exception for every rule. It’s no wonder the hyphen is often misused. To summarize:
- Do not use hyphens in place of em dashes.
- For ranges of numbers or open compounds, use the en dash.
- Do not hyphenate the adverb very or adverbs ending in –ly.
- Never put spaces around hyphens—except for suspended hyphens.
- Always consult the house dictionary for words you are unsure of.
- If in doubt, use the hyphen only if it will help avoid confusion.
For more on when to use (and not use) hyphens, the Chicago Manual of Style has a 12-page hyphenation guide that gives rules and examples for every just about every instance and combination of words. To learn more about when to hyphenate compound words, read my blog Open, closed, or hyphenated? Clearing up the compound confusion.