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Separated by a Common Line—The Hyphen as a Well-known Grammar Challenge

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The rules of using a hyphen are quite puzzling. We shed a light on where to put an obligatory hyphen, and when to avoid the punctuation mark.

When to use a hyphen correctly
A Hyphen is a Powerful Device to Combine and Separate Words at the Same Time.

A hyphen—like many other punctuation marks—should help us to navigate between the words and sentences of our texts. Luckily, there are some clearly defined cases that automatically invoke the use of a hyphen. In other examples, a hyphen is not mandatory, but helpful for the readers. Let’s have a look at the distinct instances first.

Hyphenated Numbers and Fractions (Numerals)

Try to remember to hyphenate when spelling out numbers between twenty-one and ninety-nine. Every one of them has a hyphen between the first, and the second digit. Fractions and ordinal numbers require a hyphen, too.

Thirty-one plus forty-five equals seventy-six.
You’ll need two-thirds of Parliament.
He was second-best.

Compound Adjectives with Hyphens

Whenever you encounter an adjective that consists of two parts (an adverb + an adjective), its spelling primarily depends on the position of this construction. Compare these two sentences:


George Orwell was a well-known author.

George Orwell was well known for his novels.

If the adjective comes right before a noun, it becomes hyphenated in order to avoid possible confusion. If, on the other hand, the two-part adjective stands alone, it doesn’t have a hyphen. This distinction refers to so-called attributive and predicative adjectives.

Prefixes that indicate this hyphenated construction:
“well-”, “ill-”, “little-”, or “much”

Whenever you want to use two proper adjectives simultaneously, a hyphen is needed for this parallelism:

My new jacket is blue-green at the bottom, and light-blue on top.

That’s not the case if adjectives are specified through a preceding noun:

I brought you some salmon pink flowers.

Kindly note that some people tend to put the hyphen arbitrarily.

I brought you some salmon-pink flowers.

If a whole phrase serves as a modifier, it usually gets hyphenated to symbolize the unity:

state-of-the-art, over-the-top, easy-to-handle

Compound Nouns with and without Hyphens

Look out for prefixes like
“pre-”, “pro-”, “anti-”, “non-”, “post-”, “ex-”, “half-”, “self-”, “all-”, “full-”, “part-”, “mid-”, “high-”, and “low-”.

These nearly always come separated from the noun by a hyphen:

The high-season of this region is between mid-September and mid-November.

One part of this two-tier construction may also be a digit, a special character or a single letter:

She gave us a boring 45-minute speech about physics.
I wouldn’t wear this t-shirt.
You have big $-signs in your eyes.
(Please note: This is usually informal.)

Some compound words appear in their hyphenated form in order to distinguish them from other similar words.

Mother-in-law, drive-in, walk-through, real-time, mayor-elect, editor-in-chief.

Other compound words you’ll never find with a hyphen:

Life insurance, real estate, lifestyle, doorbell, setup.

Non-Mandatory Use of the Hyphen

The following cases show examples of a more or less voluntary use of the hyphen. When you decide to include a hyphen, this generally helps to avoid confusion caused by ambiguity. For compound nouns (such as nationalities), there are a couple of examples that might require a hyphen:

flowerpot or flower pot or flower-pot

Occasionally, a hyphen supports the distinction between two homographs (words with an identical spelling):

After we re-view the movie, we’re able to write a review properly.

Moreover, the exact position of the hyphen determines the meaning of a given sentence.

Please compare

The staff has to work twenty four-hour shifts a week.

The staff has to work twenty-four-hour shifts a week.

Obligatory Hyphen Optional Hyphen
Numbers (21-99) and fractions Compound nouns like flower-pot
Attributive adjectives with “ill-”, “much-”, “well-” Distinction of homographs
Parallel adjectives like blue-green Adjectives which are specified by a nounsalmon-pink
Compound nouns with “pre-”, “pro-”, “anti-”, “non-”, “post-”, “ex-”, “half-”, “self-”, “all-”, “full-”, “part-”, “mid-”, “high-”, and “low-”; with digits, single letter, or special characters. Distinction between two sentence meanings
Some compound nouns like walk-through
Modifiers of three or more words

Since the rules of English hyphenation appear to be fairly complicated, LanguageTool will provide you with a well-deserved and much-appreciated overview on all the spelling challenges. It’ll remind you of all mandatory hyphens, but only give you some advice on the voluntarily set hyphens. Moreover, don’t worry about mistaking hyphens and dashes—LT helps you also to distinguish them.

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