The Basics

[1] To break a word at the end of a line. (Always split between syllables.)

         Note: Although a hyphen is correct in this function, I strongly advise against splitting words at the end of lines. It is a better
                  practice to simply start the word on the next line. Leave the typesetting to typesetters.

Beyond the Basics

[2] Numbers: hyphenate numbers twenty-one through ninety-nine

         Twenty-eight
         Three hundred and thirty
-five

         Also take a look at these examples   (see [4] Compounds)
 
                    third
-floor office
                    fifty
-meter race
                    fourth
-largest plane
                    13
-piece band
                    some forty
-odd pieces or so

[2] Fractions: hyphenate in noun, adjective, and adverb forms except when the second element is already hyphenated

         
one-half
         three
-quarters

         
Exception: When discussing the individual parts, do not hyphenate

                    We cut the pizza into four quarters; Dave took three quarters and Jan took one.
  
         
Note: Compounds formed with fractions are treated per rule [4]--hyphenated only when adjectival and preceding the noun
          
                    quarter-mile run
                    an eight note

[3] Prefixes or suffixes: normally joined to the root without a hyphen
 
E.g.:  ante, anti, bi, bio, co, counter, cyber, extra, hyper, infra, inter, intra, macro, mega, meta, micro, mid, mini, multi, neo, non, over, post, pre,
         pro, proto, pseudo, re, semi, socio, sub, super, supra, trans, ultra, un, under

         Antihero
         midthirties
         pseudomodern
      
         
coauthor

         Exception 1: If doing so would double A's or I's (but not O's, or E's)

                    anti-intellectual              ("i" next to an "i"--a hyphen is needed
                    anticrime                      (no hyphen needed)
                    antianxiety                    (no hyphen needed)
                    proactive                       ("o" next to "a", no hyphen)
                    preemployment              ("e" next to "e", no hyphen)
                    coordinate                     ("o" next to "o", no hyphen)

                    
Exception to [Exception 1]: co-op, de-emphasize

         Exception 2: If doing so would triple a consonant

                    fall
-like weather             (3 L's-hyphen needed)
                    childlike enthusiasm      (no hyphen needed)

         
Exception 3: If the resulting word might be misread
         
                    
pro-life

         
Exception 4: If the resulting word be a homograph (spelled the same as a different word)
       
                    re
-creation (meaning to create again) recreation (meaning enjoyment)
                    re
-lease (to lease again) release (to set free)                  
         
         
Exception 5: If the root is capitalized

                    anti
-American
                    American
-like

         
Exception 6: ex (meaning former), all, half, self --generally hyphenated (before or after a noun) unless already a single word (a closed compound)

                    ex
-wife
                    all
-around
                    half
-asleep, half-dollar     (but halfhearted, halfway, etc.--check your dictionary to determine closed compounds)
                    self
-control                     (exceptions: selfish, selfless)

         
Exception 7: quasi (only when used as an adjective)
        
                    
quasi-scientific discovery (adjective)
                    a quasi success             (noun--so no hyphen)
        
         Exception 8: repeated terms in a double prefixes

                    sub-subentry
         
         
Exception 9: before a compound term

                    non-self-sustaining
                    pre
-Vietnam War

[4] Compound modifiers that modify a noun: two or more words that together express a single idea are hyphenated if they precede a noun.
  (Primary reference for this entry was Bartleby.com & Chicago Manual of Style)

         open-mouthed kiss        ("open" modifies "mouthed," not "kiss")
         ill
-tempered dog              Note: these last two examples are a word joined to a past participle. Always hyphenate when preceding a noun.
         well
-kept secret
         brown
-eyed girl
         well
-known poet            (would not be hyphenated if it followed the noun. E.g., The poet is well known)
         best
-loved songs
         ill
-advised rescue           (The rescue attempt was ill advised.)
         so
-called test
         high
-quality jewelry        (adjective+noun)
         low
-cost housing
         twenty
-year-old man
         hundred
-dollar gift
         rust
-resistant metal
         all
-American athlete
         ever
-blooming roses
         real
-life experience        (adjective+adjective)
         much
-loved coach
         better
-looking car          (comparatives -er)
         best
-running motor        (superlatives -est)
         over
-the-counter drug     (adjectival phrases-hyphenated when preceding a noun)
         she gave me a come
-on-over-and-give-me-a-kiss look          Phrases used as adjectives preceding a noun   
         quicker
-then-usual reply              Note: familiar phrases are usually hyphenated regardless of function or position  
         Stop being a stick
-in-the-mud.     (hyphenated because it is a familiar phrase, otherwise would not have been)
         here
-today-gone-tomorrow attitude
         a per diem allowance                  
Exception: foreign phrases are not hyphenated
         four
-year-old boy                        Note: age terms are hyphenated in both noun and adjective forms
         a four
-year-old                              "
         hydrogen chloride solution           
Exception: chemical terms are not hyphenated
                         
         
Colors: considerable disagreement abounds regarding colors. The three theories are as follows:
                    
1. Chicago Manual- color compounds are not hyphenated (except established expressions like black-and-white appearing before a noun
                    
2. American Heritage Book of English Usage- color compounds are always hyphenate (except -ish, which is only hyphenated when
                        preceding the noun  (
Words Into Type agrees with this usage)
                    
3. Treat color compounds like any other compound modifier and only hyphenate when acting as an adjective preceding a noun

         
Test: one of the two (or more) modifiers should not make sense (in the original context) if paired alone with the noun. If it does, you are dealing with
                 either coordinate or cumulative adjectives and should not hyphenate.

                    She wears high
-quality jewelry.         ("high jewelry"--does not make sense.)
                    He wore a blue wool sweater.           ("blue sweater" and "wool sweater" both make sense. These are cumulative adjectives. No hyphen.)
       
         
Exception 1: If the adverb in an adverb/adjective or participle compound ends in -ly don't hyphenate.

                    carefully worked canvass
                    finely tuned machine
                    brilliantly crafted plan
                  
         
Exception 2: don't hyphenate after very, most, least, more, less

                    very conservative views
                    most efficient method
                    least skilled artist

         
Exception 3: if the compound modifier is universally known and understood and/or there is no possible confusion of misreading, don't hyphenate.

                    high school class            (Universally understood)
                    chocolate chip cookie                    "
                    third world country
                    income tax form

         
Exception 4: compound modifiers formed completely of capitalized words should not be hyphenated.

                    African American child

         
Exception 5: if the compound is itself modified, don't hyphenate.
       
                    Dave is a hard
-working cop.
                    Dave is an extremely hard working cop.      (No hyphen)

         
Exception 6: If the hyphen would look clumsy, it can be omitted, assuming no confusion results. (This generally applies to names.)

                    bubonic plague outbreak
                    chemical engineering degree

         
Exception 7: number + possessive noun- not hyphenated

                    one week's pay
                    three hours' work

         
Special Note: If the compounded adjective ends in a -d then omit the d
          
                    
freckle-faced boy (instead of freckled-faced boy) the boy with the freckled face
                    dimplecheeked girl (instead of dimpled-cheeked girl) the girl with the dimpled cheeks

         
Note: remember, compounds are not hyphenated if they follow the noun instead of precede it.

                    
Exception: some compounds are considered permanent and are hyphenated even if they follow the noun they modify.
                                     
 (these are best identified via dictionary)

                               middle-aged
                               old-fashioned

         
Style option: compounds can also be hyphenated when they follow the verb "to be."  (check your publisher's style sheet)
    
                    
That plan is short-sighted.

[5] Compounds with specific terms
 (Reference: Chicago Manual of Style)

         ache- always closed. E.g. toothache, stomachache
         
all- adjectival phrases hyphenated before or after a noun, adverbial phrases open. E.g. all-out effort, all along
         book- open unless in the dictionary. E.g. coupon book, reference book, checkbook, cookbook
         
borne- normally closed, but hyphenated after words ending in b and after words of three or more syllables. E.g.waterborne, mosquito-borne, cab-born
         
century- standard compound modifier- hyphenate when acting as an adjective and preceding a noun. E.g twentieth-century literature
         cross- noun, adjective, and adverb forms hyphenated, except some permanent compounds. E.g cross-reference, cross-country, crossbow
         
e- hyphenate. E.g. e-mail, e-commerce
         
elect- usually hyphenate unless the name of the office consists of two or more words. E.g. Mayor-elect, county assessor elect
         
ever- hyphenate before a noun (except some permanent compounds): ever-ready help, everlasting
         
ex- hyphenate. E.g. ex-wife
         
fold- closed unless formed with a hyphenated number. E.g. fourfold, twenty-five-fold, 150-fold
         
foster- standard compound modifier (hyphenate when acting as an adjective preceding the noun. E.g. foster mother, foster-family background
         

[6] Compounds by type

         Compass points-
closed unless three are combined.

                    northeast
                    east
-southeast
          
                    
Note: when the dash is taking the place of the word to it should be an en dash
                 
                               The river runs north
--south.    ("--" is used, somewhat incorrectly here, do represent an en dash instead of a hyphen)

         Family relationships-        

                    Grand-grandmother, grandfather            (always a closed compound, regardless of position or function)
                    Great
-great-grandmother                      (always hyphenated, regardless of position or function)
                    Stepmother                                        (always a closed compound, regardless of position or function)
                    Half sister                                           (open as a noun, hyphenated as an adjective preceding a noun)
                    Foster mom, foster
-family background   (open as a noun, hyphenated as an adjective preceding a noun)

[7] Normally open compound nouns: may be hyphenated for clarity if preceded by an modifying adjective.
(Primary reference for this section was Bartleby.com)
   
         wine cellar (no hyphen)
         underground wine
-cellar (add a hyphen because of the preceding adjective)
         house cat
         gray house
-cat
         broom closet
         hidden broom
-closet

Exception: when a compound modifier begins with an ly adverb, no hyphen is used.

         freakishly dressed punk star

Note: some nouns are permanently hyphenated, regardless of position or modifiers. (Refer to dictionary)
      
         fact
-finding

[8] To indicate something spelled out

       The banner read "W-i-l-l-y-o-u-m-a-r-r-y-m-e."

Syntax

No spaces before or after.

Hanging hyphen: when the second part of the hyphenated expression is omitted, the hyphen is retained

       fifteen
- and twenty-year mortgages
       five
- to ten-minute intervals
       both over
- and underfed cats

en dash in place of a hyphen in a compound adjective when one or more of its elements is an open compound or when two or more of its elements are
                                         hyphenated compounds

       post
--World War II decades
       a nursing home
--home care policy
       a quasi
-public--quasi-judicial body
       non
-English-speaking

Usage Key

Misuse

Let's Talk Style

Let's see how the pros use it
Hyphen (-)
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