Many people can comfortably go through life without ever knowing the difference between a hyphen, a dash, and whether that dash is an ‘en’ dash or an ’em’ dash. If you are reading this article, you are not one of them. If you are engaged in academic or professional writing, it is your business to use these punctuation marks correctly, just as one should know how and when to use any other character of punctuation or rule of grammar.
This post will look at the hyphen first, when to use it and when not to use it, and then at the two types of dashes.
Hyphens
Hyphens are punctuation marks that are used both to join words and to separate the syllables of a single word.
Compound words
In compound words, hyphens are used to join two or more words together. This occurs with nouns that are made of two words that habitually appear together as one:
- a mother-in-law
- a home-owner
- a middle-man
- an editor-in-chief
- a hobby-horse
- a mind-set
- self-esteem
- a twelve-year-old
Grouping these words together with hyphens aids comprehension in a sentence. Consider the following unhyphenated example:
- The mother in law of the editor in chief of the twelve year old newspaper spoke off the record to me about her state of the art technology.
- The mother-in-law of the editor-in-chief of the twelve-year-old newspaper spoke off-the-record to me about her state-of-the-art technology.
Furthermore, hyphens can join two or more words to create adjectives and adverbs that modify a noun together; these are known as compound modifiers:
- a fast-paced film
- a high-quality product
- a well-placed hyphen
- a twelve-year-old dog
- a face-to-face meeting
- a state-of-the-art technique
- a well-known actress
The act of joining two words together in this way shows the reader that they function as one word in this instance. Usually, when a noun has multiple attributes, these will be listed with a comma to divide them:
The phrase, a modern, expensive, blue product describes a product with three attributes: it is blue, modern and expensive.
A high-quality product describes a product that is ‘high-quality’, not high and quality; it cannot be described as a high product, therefore the word ‘high’ needs to be compounded with the word ‘quality’ to show that, in this instance, the two words function as one adjective together.
Writing age with hyphens
However, it is important to know when not to use a hyphen:
- I have a twelve-year-old dog.
The above words are hyphenated because the words are functioning together as one compound adjective.
- The boy is a twelve-year-old.
- You know what twelve-year-olds are like!
Likewise, the above examples function as compound nouns.
On the contrary:
- My son is twelve years old.
- I am now over forty years old.
In the above examples, no hyphens are necessary because each word in those sentences has an individual function.
Nevertheless, remember that when numbers (or fractions) are written as words, they must be joined together with a hyphen to indicate that they represent one number:
- I am forty-seven years old.
- twenty-one
- two-thirds
- forty-seven
For more detail on adjective order and placement in sentences, please see the linked post.
In addition, hyphens are used with some prefixes to clarify meaning:
- re-examine
- co-worker
If the above words had been written without a hyphen, a reader would experience confusion, but a well-placed hyphen avoids this.
Similarly, hyphens can be used to distinguish between words that have the same letters but different meanings:
- recover (to get better or to find)
- re-cover (to put a new cover on)
- I have recovered from my illness.
- The sofa has been recovered by the police. (It may have been stolen)
- The sofa has been re-covered.
The use of a hyphen in the examples above creates a clear distinction between possible interpretations.
When not to use a hyphen
When a compound adjective follows a noun in a sentence, there is no longer a need for a hyphen:
- She is a well-known actress.
- It is a poor-quality product.
This is because the previously compounded words now fulfil two separate functions within the sentences:
- The actress is well known.
- The product is of poor quality.
The reordered sentences mean that the adverb and adjectives are no longer functioning as a compound modifier but are performing their functions individually within the sentence:
- The quality of this product is high.
In addition a hyphen should not be used within a compound modifier when the adverb ends in -ly:
- A high-quality product.
But:
- A highly qualified teacher.
Dashes
Dashes come in two types: the en dash (–) and the em dash (—). They are named thus because the en dash is about the length of the letter -n and the em dash is approximately the length of the letter -m. All dashes are longer than a hyphen.
The en dash is primarily used to represent a range of values, such as numbers, dates or time:
- 10–20 pages
- Monday–Friday
Notice that, just as with the hyphen, no space is used with the en dash.
While it is important for proofreaders, academics and professional writers to understand the difference between these on a word-processor, when writing by hand, a hyphen and an en dash will be almost indistinguishable.
The em dash is longer than both the en dash and the hyphen and has a somewhat different use. It is often used as a punctuation character that indicates a break in thought, to emphasise information or to set off parenthetical statements:
- The weather—hot and humid—made it difficult for us to enjoy the outdoor activities.
- She finally achieved her goal—after years of hard work.
Em dashes are often used to create a more abrupt break in the sentence compared to parentheses or commas.
An em dash is usually written without a space on either side of it; however, there are some style guides, such as those of many newspapers, that prefer the use of a space before and after the em dash, so always consult your client or instructing party.
Conclusion
In summary, hyphens are used to join words to create compound words or adjectives, or for separating syllables within a word that might otherwise be confused with a similar word. Dashes are not used for this purpose.
Hyphens are shorter than both en dashes and em dashes. En dashes are used for ranges, while em dashes are used as a punctuation character to set off information or indicate a break in thought.
Hyphens are only used with words that create a compound word or compound modifier together; if the words are functioning individually within a sentence, they should not be hyphenated. In addition, if an adverb ends in -ly, it should never be hyphenated.
If you have any questions or comments, please do enter them below.
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https://dictionary.cambridge.org/dictionary/english/