Hyphens are one of those argument-inducing areas of the English language that has vocal parties on either side of any issue. Is the glass half full or is it half-full? Do we go over the proposal with a fine-tooth comb, or with a fine tooth-comb? (Or is it a finetooth comb?) Any set or rules, even ones that are discussed in a formal style manual, will likely end up being refuted in another style manual of equal clout.
The fact is, there’s really no set of hyphen rules on which every person can agree. Following are a few of the more common rules, and some guidelines to follow when deciding yourself whether or not to use a hyphen.
A hyphen should be used in order to create an adjective if the phrase comes before the noun in a sentence. However, the hyphen should not be used if the phrase follows the noun in the sentence. A well-respected CEO gets a hyphen, whereas a CEO who is well respected does not. A widely-known author is a hyphenated author, but an author who is widely known gets no hyphen at all. This is the most common rule of hyphenation, and among the most misunderstood, but nearly all authorities would agree on it.
If two words are inextricably linked, you can choose to hyphenate them (or you may combine the words together). Book-case, for instance, may properly be written as bookcase. Even the prefix anti- is sometimes used similarly, as in anti-discrimination (or antidiscrimination). The hyphen is necessary if the words are not combined into a single compound word. There are, of course, exceptions to the rule. Most prefixes, such as ex- and sometimes anti-, are used with hyphens instead of making the words compound. When one of the words is a proper noun, always hyphenate. Un-American never becomes unAmerican; the hyphen is necessary to avoid confusion.
On the topic of the avoidance of confusion, hyphens can be useful. “Tom pulled an issue off the dirty magazine-rack” has a dramatically different meaning than “Tom pulled an issue off the dirty-magazine rack.” In this instance, the meaning of the sentence would be ambiguous, at best, without the addition of the hyphen. “The baseball player re-signed his contract” is almost the exact opposite of “the baseball player resigned his contract.” Simply put, use your common sense.
Some nouns, such as attorney-at-law, require hyphens in order to make the noun look complete. Compound numbers and fractions use hyphens all the time: three-fifths and twenty-five should contain hyphens. Other compound words, especially when they appear before nouns in a sentence, will be hyphenated. These include such common phrases as on-the-fly, on-the-go, out-of-date, and others. Hyphens are also used to break words apart between syllables at the end of a line. If you’re a stickler for hyphenation, it’s best not to use spell-check, or to justify the words in the center of a page. The hyphens created by your computer will at best be awkward, and at worst completely incorrect. Let the computer leave hyphens to you, the hyphen expert.
This leads us to a final word. Compound words are tricky things, and the way they’re written changes over time. Often, a compound word will start out as two words and then become a hyphenated phrase before it ultimately ends up as a true one-word compound. The newest version of any dictionary of merit will help you to make the distinction. In the instance of fine-tooth comb, for example, the most commonly accepted hyphenation occurs between “fine” and “tooth.” However, according to Kingsley Amis, even this commonly accepted form is incorrect: the expression, according to him, was originally “fine tooth-comb.” In this case, feel free to use whichever you prefer. In most cases, you’ll simply want to follow your dictionary’s instructions on matters of compound words.