Using Hyphens

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The Rules for Using Hyphens

Hyphens are joiners. They are used to join the following:

• the words in a compound adjective (e.g., four-page document)
• the words in a compound noun (e.g, ice-axe)
• a prefix to a word root (e.g., anti-vaccination groups)
• the words in a single number or fraction (e.g., sixty-six, two-thirds)
• adjectives with a shared second element (e.g., a one- or two-page document)

Six Ways to Use Hyphens

Hyphens are used in six ways:

(1) To join the words in a compound adjective.

• six-foot table
• silver-service waitress

(2) To join the words in a compound noun.

• passer-by
• paper-clip

(3) To join a prefix to a word.

• re-establish
• ultra-expensive

(4) To join the words in a compound verb.

• to ice-skate
• to spot-check

(5) To help with the reading of numbers and fractions.

• one-third
• twenty-four

(6) To show that list items share a common second element.

• two-, three-, and four-bedroom houses
• two- or three-fold

Use of Hyphens Explained in Detail

A hyphen is a punctuation mark used as a joiner. A hyphen is typically used to join the separate parts of a compound word to make it clear that it's one entity. (A compound word is a word made up of more than one word.)

(1) Using Hyphens in Compound Adjectives

A hyphen joins the words in a compound adjective. (A compound adjective is a single adjective made up of more than one word.)

• free-range eggs
• A eight-seater taxi
• A far-too-chatty individual
• six-foot table
• My single-minded aim is to give existence to fantasy. (American-Swedish sculptor Claes Oldenburg)
• There's a difference between a free market and free-for-all market. (Senator Bob Menendez)

Read more about compound adjectives.
Read more about hyphens in compound adjectives.
Read about alternatives to hyphens in compound adjectives.

(2) Using Hyphens in Compound Nouns

A hyphen can be used to join the words in a compound noun. (A compound noun is a single noun made up of more than one word. Some compound nouns are hyphenated.)

• It needs a paper-clip to hold the ticket in place.
• I am looking after a two-year-old.
• History is full of inevitable front-runners who were inevitable until they weren't. (Politician Martin O'Malley)
• Behind every successful man stands a surprised mother-in-law. (French writer Voltaire)

Lots of compound nouns are unhyphenated (i.e., one word), and some are two words.

• wheelchair
• hot dog

Read more about compound nouns.
Read more about hyphens in compound nouns
Read more about forming the plurals of compound nouns.

(3) Using Hyphens in Prefixes

A hyphen can be used to join a prefix to a word.

• ultra-expensive
• re-establish
• co-opt

Most prefixed words are unhyphenated.

• cooperate
• defuse

Read more prefixes.
Read more about hyphens in prefixes.

(4) Using Hyphens in Compound Verbs

A hyphen can be used to join the words in a compound verb, especially verbs formed from two nouns.

• To gift-wrap
• To ice-skate
• I was court-martialled in my absence and sentenced to death in my absence, so I said they could shoot me in my absence. (Irish playwright Brendan Behan).

Compound verbs are far less common than compound adjectives and compound nouns. They are often invented by the writer to add a bit of flair.

• She will eyebrow-beat him into submission.
• He cold-shouldered me when I was fist-pumping his team mates.

Not all verbs comprising two words are hyphenated. Do not use a hyphen with a phrasal verb . (A phrasal verb comprises a main verb and another word, e.g., to break out, to drop off.)

• Never give in, and never give up. (American politician Hubert Humphrey)
(These are phrasal verbs. They are correct without hyphens.)

Read more about compound verbs.

(5) Using Hyphens in Fractions and Numbers Written in Full

Hyphens are used in fractions written out in full.

• one-third
• two-thirds
• four-tenths

When numbers are written out in full, hyphens are used in all numbers between 21 and 99 (less those divisible by 10).

• fifty-one
• two hundred thirty-four
• three thousand five hundred sixty-seven

You might be wondering why there's no "and" before "thirty-four" and "sixty-seven." It is a common practice to omit the word "and" (even though you might say it) because for many (especially Americans), "and" denotes a decimal point. In other words, some take "two hundred and twenty-one" as 200.21 not 221. (Interestingly, if you follow this practice and write out all the numbers, you'll reach 1000 before using the letter "a".) Read more about writing numbers in full.

(6) Using Hyphens with List Items Sharing a Common Second Element

A hyphen can be used before a common second element in all but the last word in the list.

• You can buy a two-, five- or seven-seater version of this car.
• If our monarchy can show democracy that leads to a two-, three-, four-party system (left, right and centre), then the Brotherhood will no longer be a contender. (Abdullah II of Jordan)

These three examples show this technique with compound adjectives that would ordinarily contain hyphens if written out in full. However, this technique can be used with compound words that wouldn't ordinarily contain hyphens.

• I don't care if you're Aqua-, Bat- or Superman, Mr Clayderman. You're still late.
• It will increase two- or threefold.

Why Hyphens Are Important

A hyphen is typically used to show that the joined words are a single entity (e.g., a single adjective or a single noun). This has the following three benefits:

1. It makes your text easier to read.
2. It removes the possibility for ambiguity.
3. It showcases your writing skills.

Here are five noteworthy points related to hyphens.

(Point 1) Use a hyphen if the unhyphenated version of a compound adjective would be ambiguous.

British readers will expect you to use hyphens with compound adjectives, but, in the US, readers are more lenient. In fact, it is common to see compound adjectives without hyphens in both regions, especially with well-established terms that are unlikely to make a reader stall (e.g., "ice cream stall," "twentieth century building"). So, it is not a serious error to omit a hyphen from a compound adjective. That said though, when the unhyphenated version of a compound adjective is ambiguous, you must use a hyphen to link its words.

• a small business grant
(This is ambiguous. Does this mean a small grant for business purposes or a grant for a small business?)
• a small-business grant
(With the hyphen, it is clear that we're talking about a grant for a small business. It could be a large grant.)

Here is another example:

• I have a concealed weapons permit.
(This is ambiguous. Does this mean a permit for concealed weapons or a permit hidden from view?)
• I have a concealed-weapons permit.
(With the hyphen, it is clear we're talking about a permit for concealed weapons.)

Here is another example:

• a heavy water reactor
(This is ambiguous. Is this a heavy reactor for use with water or a heavy-water reactor?) (Note: "heavy water" is deuterium oxide.)
• a heavy-water reactor
(The hyphen makes it clear this is a deuterium-oxide reactor.)

(Point 2) Don't use hyphens with adverbs that end "-ly."

When using an adverb to modify an adjective (e.g., "perfectly formed ring"), some writers feel the need to use a hyphen (e.g., "perfectly-formed ring"). With adverbs ending "-ly" (and there are lots) and the word "very," that's a mistake.

• It is a wonderfully-decorated tree.
• Paula is a very-talented student.

This applies only to adverbs ending "-ly." It does not apply to adjectives ending "-ly."

• It's a friendly-looking, family-run business.
("Friendly" and "family" are not adverbs.)

Also, use a hyphen for adverbs that could feasibly be adjectives (e.g., "well," "fast," "best").

• Lee is the best-known player on the pitch.
(Here, Lee is known better than any other player. "Best" is an adverb.)
• Lee is the best known player on the pitch.
(Few would differentiate this from the hyphenated version, but it could feasibly mean that Lee is the best of all the known players, in which case "best" would be an adjective. If you substitute known with "chubby," it will highlight "best" as an adjective.)

This issue commonly crops up with the adverb "well," which is also an adjective meaning healthy.

• We're looking at a well-developed fetus.
(This means the fetus is significantly past the embryonic state.)
• We're looking at a well developed fetus.
(This could mean the same as above or possibly a healthy and developed fetus.)

This situation occurs most commonly with "well" (e.g., "a well-fatted calf"), but it can occur with "fast" and "best" too (e.g., "fast-changing wind," "best-known actor").

A Safe Rule

This rule will see you right:

Use a hyphen with "well" when it's modifying an adjective. The likelihood of needing the adjective "well" before another adjective is low.

(If you're not prepared to gamble on this low likelihood, substitute "well" with "healthy," and if your sentence makes no sense, put "well" back in and use a hyphen.)

(Point 3) When using an expression like "three-and-a-half," don't join your adjective to your noun with a hyphen.

When used as compound adjectives, expressions like "three-and-a-half" and "two-and-a-quarter" are often hyphenated to make it clear they're one entity. If you decide to use hyphens in such a term, don't join your adjective to your noun with a hyphen.

• He wants four-and-a-quarter-billion.
• He wants four-and-a-quarter billion.
(Here, "four-and-a-quarter" is a compound adjective modifying the noun "billion." Joining them with a hyphen would be as wrong as writing "He wants a nice-car.")

Be mindful, however, that your compound adjective might not end when the expression like "four-and-a-quarter" ends.

• He wants four-and-a-quarter-billion pounds.
(This time, the hyphen between "quarter" and "billion" is correct because "billion" is now part of the compound adjective modifying "pounds.")

Be particularly careful to group all the parts of your compound adjective when writing ages.

• She's a twenty-four-year-old woman.
(All too often, the hyphen after "year" is mistakenly omitted.)

(Point 4) Use your spellchecker smartly to spell compound nouns correctly.

Some compound nouns are one word (e.g., "snowman," "aircraft"), some are two words (e.g., "fish tank," "cell phone"), some compound nouns are hyphenated (e.g., "know-how," "runner-up"), and some have more than one acceptable spelling (e.g., "paper clip," "paper-clip," and "paperclip").

Your spellchecker will not test the two-word version or the hyphenated version as a single entity. In other words, it will not highlight "air craft" or "air-craft" as an error (even though it should be "aircraft"). So, you have to test the one-word version. If your spellchecker doesn't like the one-word version, you have a choice between the two-word version and the hyphenated version. Often, this really is your choice. Use a hyphen for clarity (i.e., to make it instantly obvious it's a single entity) and to eliminate ambiguity.

• pen friend / pen-friend
(The hyphenated version is clearer. It stands out as a single entity, making it easier to read.)
• cooking oil / cooking-oil
(The hyphenated version makes it clear the oil is not cooking.)

(Point 5) Use your spellchecker and your instinct to determine whether to use a hyphen with a prefix.

If you're unsure whether to use a hyphen with a prefix, start by not using a hyphen. However, use a hyphen if the unhyphenated version:

• Looks too unwieldy for your taste ("antiaircraft" might be an example).
• Is highlighted as a spelling mistake by your spellchecker (e.g., "reestablish").
• Is ambiguous (e.g., "Re-cover the sofa" is not ambiguous, but "Recover the sofa" is.)

Read more about using hyphens with prefixes.

Key Points

Video Lesson

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