What Are Hyphens? (with Examples)

A hyphen (-) is a punctuation mark used to join the separate parts of a compound word. A hyphen is a joiner.

A hyphen is used to join the words of a compound adjective (e.g., five-page document), to join the words of compound noun (e.g., cooking-oil), and to join a prefix to a word (e.g., re-examine).

One of the main functions of a hyphen is to show the joined words are a single entity (e.g., a single noun or a single adjective). A hyphen is also useful to eliminate ambiguity. For example, a hyphen makes it clear that cooking-oil is oil for cooking and not oil that is cooking.

Below is a quick overview of when hyphens are used. Click here for a more comprehensive version of this list or click on the "Read more" link with each entry.

When to Use Hyphens (A Very Quick Overview)

Below is a quick overview on when to use hyphens.

(1) Use hyphens in compound adjectives to show they are single entities.

In the examples below, the compound adjectives are shaded.
  • free-range eggs
  • two-day break
  • four-seater aircraft
Brits tend to use hyphens in compound adjectives more than Americans. It is not a grammatical error not to link the words in a compound adjective with a hyphen(s). However, it usually makes it easier to read, and it showcases your writing skills.

(2) Use hyphens in compound nouns to show they are single entities.

In the examples below, the compound nouns are shaded.
  • Nitrous oxide, commonly known as laughing-gas, has a slightly sweet odour and taste.
  • I have lost my water-bottle.
  • He was seen by a passer-by.
  • Did he marry his sister-in-law?
Often, the non-hyphenated version is acceptable too. However, using a hyphen will make your word easier to identify as a single entity, and it showcases your writing skills.

(3) Use hyphens with prefixes.
  • re-enact
  • cooperate and co-operate
  • antifascist and anti-fascist
Not every prefix requires a hyphen.

Here are the guidelines on when to use a hyphen with a prefix.

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