When to Hyphenate
  • 3-minute read
  • 28th December 2014

When to Hyphenate

“Hyphenation” is a term for linking two words with a hyphen to make a compound word. In this context, “compound” simply means two separate words have been joined together. But when should you hyphenate a word? We’ll explain the basics below.

Compound Adjectives

Compound adjectives are formed by joining two words (e.g., “good-looking,” “power-hungry” or “accident-prone”). Further examples include:

  • Free-range
  • Part-time
  • Long-term
  • Well-known

Compound adjectives can be composed of more than two words, making them more like phrases:

  • Tongue-in-cheek
  • Happy-go-lucky
  • Devil-may-care

Compound adjectives like these are often only be hyphenated if they appear before what they are describing in a sentence. For example, the compound adjective in “The well-known artist Whistler…” could also be used without a hyphen later in the sentence: e.g., “The artist Whistler was well known…”

However, some modifiers are hyphenated regardless of where they appear in a sentence, such as “error-free” (e.g., “the error-free paper” and “the paper was error-free” are both correct).

Compound Nouns and Verbs

It is more difficult to know when to hyphenate nouns and verbs. In many cases, it is simply a matter of convention (e.g., “mother-in-law”). The best thing to do with these terms is check a dictionary. If you find a term where the hyphen is optional, your main guideline should be consistency.

Many words that begin with the prefixes “non-,” “pre-,” “de-,” or “re-” are hyphenated, but this is only necessary when it prevents a letter clash.

For example, we hyphenate “re-evaluate” because “evaluate” starts with the same letter that precedes it. But we do not hyphenate “retry” because there is no letter clash. This isn’t always true, but it is a good rule of thumb (and you can always check a dictionary if you’re not sure about a word).

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Hanging Hyphens

A hanging or suspended hyphen can be used when two compound terms contain the same second element. For instance, a company might say “we offer five- and ten-year mortgages.” Here, the hyphen after “five” shows that we mean “five-year and ten-year mortgages” but didn’t want to repeat “year.”

This can also be done with closed compounds, such as in “under- and overground trains.” Note that we use a hyphen after “under” even though the full word would be “underground,” without a hyphen.

Hyphenating for Clarity

In some cases, we also use a hyphen to ensure clarity. Omitting a hyphen can even change the meaning of some sentences. For example:

  1. I once saw a man-eating crocodile.
  2. I once saw a man eating crocodile.

The first sentence here describes a crocodile as “man-eating” (i.e., a crocodile that eats humans). The second, non-hyphenated sentence describes a man eating crocodile meat.

Rules about which words should be hyphenated can vary between institutions, though, so be sure to double check your style guide.

If you would like to have your paper checked for style, grammar and formatting errors, make use of Proofed’s specialist academic proofreading service.

Comments (4)
Racquel Marsh
6th January 2022 at 16:21
"Rules about which words should be hyphenated can very between institutions, though, so be sure to double check your style guide." I suggest changing "very" to "vary."
    Proofed
    6th January 2022 at 16:59
    Typo now fixed. Thanks, Racquel.
Mary Frances
18th May 2022 at 04:15
If someone wrote "_____, a social media public health platform, ..." should the two double adjectives be hyphenated (i.e. "...a social-media public-health platform..." or separated by a comma (i.e. "...social media, public health platform...")?
    Proofed
    18th May 2022 at 09:20
    Hi, Mary. Neither "social media" nor "public health" would typically need to be hyphenated in that context (both are well-established open compounds rather than novel compound modifiers, and hyphenation wouldn't be necessary for clarity). It terms of the comma, you only need a comma between adjectives when they are coordinate (i.e., when they modify a word in the same way). I don't think that is really the case here (assuming "social media" refers to the type of platform and "public health" refers to its purpose or focus). But this may depend on how you are using the term. A helpful test for whether adjectives are coordinate is to try placing "and" between them, so if "a social media and public health platform" sounds like a good description of what you're trying to communicate, then "social media, public health platform" would be correct. If the "and" sounds out of place, then "social media public health platform" may be more appropriate.

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