If the apostrophe is the most misused punctuation character in the English language, the hyphen must be a close second. Any good authority on grammar and punctuation will have pages and pages of rules for the use of the hyphen. This is not one of them. It’s just a list of the three most common misuses and abuses of the hyphen found on Yahoo!.
Hyphenating a word that doesn’t have a hyphen
The only way to be sure that a word should be hyphenated is to look it up in a dictionary. Nevertheless, many writers fail to take that simple, straightforward step and add a hyphen to a word that is derived from two or more words. Be sure to check out the 30 words that appear most often on Yahoo! with an unnecessary hyphen.
Adding a hyphen to an adverb ending in LY
You don’t need it. Don’t put a hyphen after an adverb ending in LY. Ever. The LY at the end of the adverb is enough to signal to your reader that it modifies the word that follows it.
She is a highly regarded editor with a rapidly expanding collection of examples of poorly written blog entries.
Omitting the hyphen in an age or adding a hyphen to an age
It seems to be a contradiction, but sometimes an age requires 2 hyphens and sometimes not. Here’s a simple rule: if the expression contains years old (note that plural years), omit the hyphens. If it contains year old (and that singular year), include two hyphens, before and after the word year.
She’s 35 years old, but she writes like a 10-year-old.
Terribly Write 
February 16, 2011 at 8:35 pm
Thanks for the information! This is great!
March 6, 2011 at 1:29 pm
These are great tips. Thanks!
March 9, 2011 at 4:14 pm
Love reading your blog! These tips are great. Bookmarking it for reference in the future.
March 10, 2011 at 1:59 am
Thank you for this information. It’s the first time I read this kind of information in a concise and easy-to-understand format. I’ve bookmarked this page.
March 17, 2011 at 8:29 pm
Thanks! This was short and easy to understand and read.
April 24, 2011 at 6:48 pm
You should add three more categories:
Mixing up hyphens and dashes.
Putting spaces around hyphens.
Adding hyphens to phrases that don’t need them. Examples:
“I’m going to pick-up my car.”
“Be sure to fill-in the shape completely.”
“Your password is need to sign-in.”
April 24, 2011 at 9:58 pm
Those are good ones! Of the three, I see Yahoo! staffers using a hyphen instead of a dash most often. They also use a hyphen to join a verb and its preposition to form what they think is still a verb (as your examples illustrate). I like your suggestions and will try to expand this list.
July 31, 2011 at 5:20 am
Great tips! Thanks for these and for your vigilence!
August 4, 2011 at 2:26 pm
Here’s a hyphen use question. A well nourished and developed patient. If it was well-nourished and well-developed patient, I would use the hyphens as I have. But in the example, the patient is both nourished and developed “well.” Was I right to leave off the hyphen between well and nourished?
August 4, 2011 at 2:57 pm
Debbie,
In your example, to be absolutely, excruciatingly correct, you would use a suspensive hyphen before the word “developed”:
A well-nourished and -developed patient
But I think it’s awkward and bound to look like an error to many readers. I’d recommend repeating the word “well” and eliminating the word “and”:
A well-nourished, well-developed patient
December 11, 2011 at 3:09 am
These is good tip for me.Thanks for information.
May 14, 2012 at 9:04 am
I have a question:
Is there a hyphen in “heaven sent”? I’ve found mixed responses concerning this, and I figured you’d know the right answer.
May 14, 2012 at 10:17 am
Hi, Lynn! If you’re using it as an adjective, it should be hyphenated, even if it doesn’t immediately precede the noun it modifies:
The gift was heaven-sent. It was a heaven-sent gift.
If you’re using it as a verb, no hyphen. (I know you knew that. I mention it only because there are other readers out there who probably could use a reminder — like Yahoo! staffers.)
Heaven sent me a gift.
May 14, 2012 at 10:42 am
Thanks!!!
May 25, 2012 at 6:11 am
I see a lot of hyphen abuse with numbers, especially on weather sites. I think this is incorrect:
“Temperatures nearly 10-degrees cooler than Thursday…”
Or “The high today will be 85-degrees.”
But “An 85-degree day” would be correct. Correct?
May 25, 2012 at 7:16 am
I have no idea why some people think a hyphen is required in expressions like “10 degrees.” As far as I can tell from consulting several authorities, the hyphen is incorrect. You are correct that the hyphen is required when the temperature is used as a compound adjective consisting of a number and a unit of measure appearing before the noun it modifies. So, “85-degree day,” “t0-foot fence,” and “3-year-old girl” are all correct. But “the temperature was 85 degrees,” “the fence is 10 feet high,” and “the girl is 3 years old.”
June 20, 2012 at 7:58 am
When is a hyphen appropriate in writing about stories of a building? I have seen it written “four stories” and “four-stories”. An example would be…”the four-story building was built in 1925 and sold for $1,000,000….” Is the hyphen needed?
June 20, 2012 at 11:41 am
The rule is the same whether you’re writing about stories of a building or the length of a home run. It should be: “a four-story building” (note that “story” is singular and the compound adjective “four-story” modifies “building”) or “the building has four stories.”
March 4, 2013 at 4:22 pm
Is the following sentence punctuated correctly?
“We are taking a mid-January vacation in mid January.”
(I know, I know: It’s redundant. But my concern is whether or not to hyphenate “mid” in the second instance.)
August 19, 2013 at 3:11 pm
In the following phrase, would the hyphens be required?: “The top-three-largest accounting firms are X, Y and Z.”
August 19, 2013 at 5:49 pm
What’s not required is the word “top” and the hyphens: The three largest accounting firms are…
August 20, 2013 at 2:38 pm
The hyphen is not always wrong with “-ly” words. E.g., “friendly-looking dog.”
August 20, 2013 at 3:03 pm
Although “friendly” ends in -LY, it is not an adverb in “friendly-looking dog” — it’s an adjective. “Friendly-looking” is a compound adjective (where “looking” is a participle functioning as an adjective), modifying “dog”, and thus should be hyphenated.
October 12, 2014 at 4:27 pm
This is great. I was just about to correct someone who wrote “poorly led groups…” I was about to put a hypen after poorly.
Thanks so much for your post and clarification.
October 12, 2014 at 4:49 pm
You’re welcome. I glad you found something useful here. Please have a look around and let me know what you think.
March 11, 2015 at 8:35 am
Which is correct: 10-Year Club or 10 Year Club. We’re debating!
April 17, 2016 at 11:01 am
My French course keeps correcting my English. Should I really write ’85’ as ‘eighty-five’ with a hyphen?
April 17, 2016 at 7:41 pm
If you’re writing out a two-part number like 85, you need to hyphenate it: eighty-five.
February 4, 2017 at 1:00 pm
How would you hyphenate “a twelve or thirteen-year-old boy”? I think a hyphen after “twelve” would be technically correct, but appear clunky.
February 4, 2017 at 1:29 pm
The hyphen after “twelve” is correct: a twelve- or thirteen-year-old boy
If you think it’s clunky, try some alternatives. I don’t know if you’re following a specific style guide, but some authorities recommend using numerals for ages: a 12- or 13-year-old boy
Or maybe you can rewrite: a boy, 12 or 13 years old,
Or: a boy, around 12 or 13,
February 4, 2017 at 1:39 pm
Thank you for the quick response!! (I am editing someone else’s work, so I’m trying not to change the original too much.) I’ll correct it and let her decide if she wants to change it.
June 30, 2021 at 3:34 pm
Terribly write, you are terribly wrong. “She’s one year old, but she writes like a 10-year-old.” “One year old” absolutely should not have hyphens. Hyphens are needed to link the words 10-year-old together into a noun. Sad that you are cheating your readers with half-baked rules.