A hyphen (-) is used in the middle of a multi-word idea or joins two related words together.

(The hyphen key is next to the +/= key on your keyboard (the same key with the underscore _ )

Use hyphens to join compound words and avoid awkward or confusing word combinations.

A hyphen (-) is used in the middle of a multi-word idea or joins two related words together.

My son-in-law owns a friendly-looking dog.

Ten Rules for Using a Hyphen

1. You should hyphenate two words if they come after a noun they modify and contain a single idea. Some grammar books will calls this a compound adjective. 

He knew she was a well-dressed lady, but until he saw her immaculately-polished fingernails, he wasn’t sure she was the right one for the job.

You do not need to hyphenate if the words come after the noun (unless the words are a generally accepted hyphenated compound). Always look up a word if you are unsure.

The lady was well dressed with immaculate nail polish.

2. Use hyphens with ages if the period of time is singular (not plural). 

I have a three-year-old child. She is three years old.

Year is singular in the first sentence, so you should use a hyphen. Years is plural in the second sentence, so you do not use a hyphen. The only exception to this is if the unit of time is one.

The one-year-old child is laughing.

In this case, the word year is singular because the child is only one, not for another grammatical purpose.

3. Use a hyphen between numbers, but do not put spaces between the numebrs and the hyphens. 

The class meets from 5:30-6:45 (not 5:30 – 6:45).

4. Use a hyphen for all compound numbers from twenty-one through ninety-nine. 

The class had twenty-four students.

The car cost twelve thousand nine hundred ninety-nine dollars.

You rarely need to spell out numbers like this—unless you have to start a sentence with a number, in which case you must spell it out. If you have a sentence that begins with a number, consider rearranging the word order to avoid it and save yourself the trouble!

Thirty-two people registered for the seminar.

The seminar had 32 people registered.

7. Use a hyphen when discussing fractions.
The vote passed with more than a two-thirds majority.

6. Use a hyphen between a double last name.

Camilla Parker-Bowles married Prince Charles.  

7. You can use a hyphen if you are being creative with a word form in order to make a point (or be funny or clever).

He found he could not yes-ma’am his way into a corner office.

He gave his dog another one of those oh-will-you-please-listen-to-me looks and sighed.

8. Use a hyphen to avoid confusion.

I re-sent that document.

Without the hyphen, this would say “I resent that document” and that may be misinterpreted!

He discovered the missing-person report.

Without the hyphen, it is not clear if he found a report about missing people or if the “person report” was missing.

9. Do not use a hyphen for adverbs that end in -ly (or very).

INCORRECT: the very-fancy dinner party or the elegantly-sculpted statue

Note: This only applies to adverbs that end in -ly, not every word that ends in -ly.

The family-owned cafe was guarded by a friendly-looking dog.

10. Try not to overuse the hyphen with commonly known phrases. Always look up a word to see if it is typically hyphenated

Hyphen Checklist

  • To join some compound words into one word when the word reflects a single concept
    • The well-known doctor gained additional recognition when the results of her top-notch research were published.
      • Hyphens are used only when the compound word precedes the noun it modifies–not when it follows it. For instance: The well-known actor was not as well known as she assumed. 
    • Mother-in-law, five-year-old, better-than-usual
  • With a small group of prefixes and suffixes
    • ex-wife, post-World War II, pre-2000, treasurer-elect
  • In numbers and fractions that have been written out in words
    • seventy-six, one thousand twenty-five, one-eighth, two-thirds
  • To avoid confusion in meaning
    • re-vision (to look at something more than one time)
  • To avoid awkward letter combinations
    • anti-integration, non-negotiable, pre-engagement
  • Do not use a hyphen in familiar compound words and terms
    • Pineapple, hometown, private school, bank account
  • Do not use a hyphen with most prefixes and suffixes
    • Prenuptial, unconscionable, collaborate

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