Compound adjectives

When we use two words together to create a single modifier, we create a compound adjective. The hyphen creates a word group that makes it easier for the reader to read and process its meaning.

Before the noun, use a hyphen.Join compound adjectives with hyphens when you use them before the noun (Notice that twelve-year-old does not, in this case, use an s):

• She wrote an eight-page essay.
• We took a fast-moving train to Santa Barbara.
• Sandra is looking for a part-time job.
• It was a well-developed research paper.
• The twelve-year-old boy is a skateboard champ.
• He’s taking a much-needed vacation.

After the noun, no hyphen.Do not use a hyphen when the adjective comes after the noun. Notice, in this case, the s on twelve years old:

• Her essay was eight pages long.
• The train to Santa Barbara was fast moving.
• Sandra’s job is part time.
• Her research paper was well developed.
• The skateboard champ is twelve years old.
• His vacation was much needed.

Exceptions to the ruleIf the compound contains a proper noun, do not use a hyphen even if it does come before the noun. If the adjective is composed of two nouns, do not use a hyphen. And never use a hyphen with a comparative (-er) or superlative (-est) or to join an –ly adverb to an adjective

• Containing proper nouns: Have you bought the State Radio concert tickets yet?
• Two nouns: They met at the Friday night dance.
• In comparisons This is a better looking rosebush.
• ly-adverb + adjective: It’s an easily understood process.

Compound adjectives sometimes “lose” their hyphens over time, becoming a single word (eye-catching to eyecatching, for example), so the only way to know for sure is to look the word up in a dictionary.