Hyphens

Compound modifiers

Use hyphenated compound modifiers before a noun. A compound modifier acts as a single unit to modify the noun. When you use a compound modifier after a noun, don't hyphenate it.

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Adverbs ending in -ly

Don't hyphenate adverbs ending in -ly except where needed for clarity.

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When to hyphenate

Don't hyphenate a word that has a prefix or suffix except in the following situations:

  • Where not doing so could cause confusion—for example, re-count, re-mark.
  • When a number or a capital letter follows the prefix—for example, non-English, pre-1500, post-twelfth graders.
  • When the prefix ends in a vowel, and the word it precedes starts with the same vowel—for example, co-op, de-energize.
  • When the prefix is self—for example, self-aware, self-important.
  • When the prefix is followed by a word that is already hyphenated.
  • When the prefix is followed by a compound word that contains a space. In this case, the space is replaced with a hyphen—for example, twentieth century but pre-twentieth-century music.

Compound words

Compound words are two or more words that are joined to form a new word. To determine whether to hyphenate a compound word, check the word list. If it's not in the word list, check a dictionary.

Range of numbers

Use a hyphen, not an en dash (–), to indicate a range of numbers. If a hyphen introduces ambiguity, use words such as from, to, and through for clarity. Don't mix hyphens with words. For information about how to represent a range of numbers that includes units, see Ranges of numbers with units.

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Spaces around hyphens

Never place a space on either side of a hyphen except when using a suspended hyphen, in which case you can leave a space after (but not before) the hyphen.

Suspended hyphens

When two or more compound modifiers have a common base, you can keep the hyphens but leave out the base for all except the last modifier. In the following examples, the base is hour.

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