Hyphens are like trailer hitches; they join two words to make them one. Hyphenation rules are in flux- to be safe, consult a recently published standard dictionary.
Use hyphens to link compound nouns:
son-in-law, best-seller, president-elect, cold-shoulder, double-up, strong-arm, blue-collar
Tip: Many compound expressions don't use a hyphen. When in doubt, consult a dictionary.
Here are few that don't require hyphens:
cabdriver, schoolchildren, waterproof, crosswalk, best man, high school, nurse practitioner
Use hyphens to connect words that function as adjectives, describing a noun:
There's a hot-blooded horse.
He refused to travel in any English-speaking countries.
That fourteenth-century tapestry is priceless.
The well-known politician spoke at many rubber-chicken banquets.
Tip: Do not use hyphens with adverbs that end in "ly."
Her sharply honed gift of public speaking got her the nod.
Do not use hyphens to link words that follow the noun:
There's a horse that's hot blooded.
He refused to travel in any countries that were English speaking.
That tapestry from the fourteenth century is priceless.
The politician, who is well known spoke at many banquets that served rubber chicken.
Use hyphens with some prefixes and suffixes: "self-," "all-," "ex-" (when it means former), "quasi-," and with the suffix 'elect.'
self-esteem all-encompassing ex-husband vice president-elect
Hyphenate prefixes when either the word or prefix begins with a capital letter:
anti-American post-Clinton era A-bomb
Use hyphens when writing out fractions and numbers.
Use a hyphen for a two-word number under one hundred:
When writing out a fraction, place a hyphen between the numerator and the denominator— except if either of them already has a hyphen:
two-thirds sixty-five hundredths
Use hyphens to make compound phrases:
holier-than-thou attitude once-in-a-lifetime opportunity
Use hyphens if there is a chance a word could be misread:
Use hyphens in technical expressions:
uranium-235 T-square light-year
Use hyphens when handwriting to divide words by syllables if you run out of space at the end of a line. One-syllable words should never be hyphenated, as well as contractions, numbers, abbreviations, or initials.
lo/qua/cious, hum/bug, ter/ri/fied, per/se/cut/ed