Punctuation III: Hyphens in Compound Words

I’ve already talked about the hyphen versus the en dash and now I will look at the hyphen in more detail, concentrating on the use of the hyphen in compound words.

Hyphens in compound words

Compound words may consist of two separate words, two words that are hyphenated, or they may have become one word through common usage. Compound words which risk being mispronounced if joined together take a hyphen (e.g. drip-proof, hat-trick). Hyphens are also used to signify an abstract rather than a literal interpretation (e.g. crow’s-feet).

When compound words modify a noun, the rules are as follows:

• Preceding the noun: hyphenate (e.g. I once owned a long-haired cat)
• Following the noun: do not hyphenate (e.g. The cat I once owned was long haired)
  

Ensure you fully understand the description you are proofreading, because a single hyphen can completely change the meaning:

• A stainless steel table is a spotlessly clean table which is made of steel
• A stainless-steel table is a table made of stainless steel
  

Do not hyphenate compounds which use an adverb ending in ‘-ly’ (e.g. They are a happily married couple).

When there is a gerund involved, use a hyphen, as the construction is describing rather than modifying something (e.g. The goat I once owned was a sun-loving goat).

There are some exceptions to the compound words rule: for example, you should not hyphenate capitalised words (e.g. I just can’t read those Old Testament stories); similarly, it is not necessary to hyphenate technical terms (e.g. liquid crystal display).

If in doubt, check in the dictionary!