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Use hyphens to connect numbers defining ages coupled with the words year-old. For example, 25-year-old, 25- to 75-year-olds.
Hyphens should be used to clarify the meaning of words. For example, when the last letter of a single-syllable prefix is a vowel and the word that follows begins with the same vowel. For example, de-emphasise, pre-eminent, re-enter.
This This is less crucial if the word is well known. Do not hyphenate cooperate and coordinate.
Use a hyphen to distinguish new words with prefixes from established words that would otherwise look the same.
Example one | Re-cover means cover again but to recover means retrieve |
Example two | Re-creation means creation anew but recreation means a leisure-related activity |
Use a hyphen with co- and ex- prefixes. For example, co-author, co-worker, ex-alderman, ex-wife.
There are instances in which compound words (words made up of two separate words) should be left without a hyphen:
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- great (great-grandparent)
- vice (vice-president)
- ex (ex-teacher)
- self (self-esteem)
- elect (mayor-elect)
- odd (thirty-odd, twelve-hundred-odd)
- all (all-seeing, all-important)
- most words containing half (half-term, half-hourly, half-measure)
- many words beginning with cross (cross-country, cross-examine, cross-index)
- semi followed by a word beginning with i (semi-isolated)
- most words beginning with non (non-academic, non-hereditary, non-state school; exceptions: nonverbal, nonfiction).