Close up the parts of a compound noun spelled as one word.

Omit hyphens in a compound noun spelled as separate words.

Hyphenate fractions, compound numbers (up to ninety-nine), and other nouns that are hyphenated in your dictionary.

Note: If using compound words that have more than one acceptable spelling (workforce and work force, for example), choose one spelling and use it consistently. If you are unsure about whether to use a hyphen, check your dictionary, or follow the common usage of professional publications in that field.