A manual for writers of research papers, theses, and dissertations, Ninth edition - Kate L. Turabian 2018
Compounds and words formed with prefixes
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Style
Compounds come in three forms: hyphenated, open (with a space, not a hyphen, between elements), or closed (spelled as one word). Choosing the right one can be difficult. The best authority is your dictionary. If you cannot find a compound there, follow the principles in the following paragraphs to decide whether or not to hyphenate. If you cannot find the form in either place, leave the compound open.
The patterns outlined below are not hard-and-fast rules. You will have to decide many individual cases on the basis of context, personal taste, or common usage in your discipline. Although much of the suggested hyphenation is logical and aids readability, some is only traditional.
20.3.1 Compounds Used as Adjectives
Some compounds are used only as adjectives. In most cases, hyphenate such a compound when it precedes the noun it modifies; otherwise leave it open.
Before noun |
After noun |
✵ open-ended question |
✵ most of the questions were open ended |
✵ full-length treatment |
✵ treatment is full length |
✵ well-read students |
✵ students who are well read |
✵ thought-provoking commentary |
✵ commentary was thought provoking |
✵ over-the-counter drug |
✵ drug sold over the counter |
✵ the third-largest town |
✵ the town was the third largest |
✵ spelled-out numbers |
✵ numbers that are spelled out |
There are a few exceptions:
✵ ▪ If a compound that would normally be hyphenated is preceded and modified by an adverb (such as very), omit the hyphen.
Before noun without adverb |
Before noun with adverb |
o a well-known author |
o a very well known author |
o an ill-advised step |
o a somewhat ill advised step |
✵ ▪ Hyphenate compounds that begin with all or end with free.
Before noun |
After noun |
o all-encompassing treatment |
o treatment was all-encompassing |
o toll-free call |
o the call was toll-free |
✵ ▪ Hyphenate compounds that end with the terms borne, like, and wide (both before and after the noun) unless the term is listed as closed in Merriam-Webster.
Hyphenated |
Closed (per Merriam-Webster) |
o food-borne |
o airborne |
o bell-like |
o childlike |
o Chicago-wide |
o worldwide |
✵ ▪ Comparative constructions beginning with such terms as more/most, less/least, and better/best should be hyphenated only when there may be confusion about whether the comparative term is modifying the adjective that follows within the compound or the noun after the compound.
Modifying adjective |
Modifying noun |
o colleges produce more-skilled workers |
o we hired more skilled workers for the holidays |
✵ ▪ Constructions that consist of an adverb ending in -ly followed by an adjective are not compounds and should not be hyphenated in any context.
Before noun |
After noun |
o highly developed species |
o the species was highly developed |
o widely disseminated literature |
o literature has been widely disseminated |
20.3.2 Compounds Used as Both Nouns and Adjectives
Some compounds are primarily nouns but can also function as adjectives when they precede and modify another noun. (Unlike some of the examples in 20.3.1, these compounds are rarely used as adjectives after a noun, and then only with a linking verb such as was or are, as in the third example below.) In most cases, hyphenate such a compound when it precedes a noun that it modifies; otherwise leave it open.
Adjective before noun |
Noun, or adjective after noun |
✵ a mountain-climbing enthusiast |
✵ mountain climbing became her specialty |
✵ a continuing-education course |
✵ a program of continuing education |
✵ a middle-class neighborhood |
✵ her neighborhood was middle class |
There are a few exceptions:
✵ ▪ Some compounds are common enough to appear as nouns in standard dictionaries either as one word or hyphenated.
o birthrate
o smartphone
o decision-making
o head-hunting
✵ ▪ For a compound that begins with e (short for electronic), ex, or self, use a hyphen in all contexts. Two exceptions: email is spelled without the hyphen, and if self is preceded by un, the compound should be closed (as in unselfconscious).
o ex-husband
o self-destructive
o e-book
o but
o email
✵ ▪ For a compound that ends with elect, use a hyphen in all contexts when the name of the office is only one word, but leave it open when the name is two or more words.
o president-elect
o district attorney elect
✵ ▪ For a compound formed by two coordinated nouns that could be joined by and, use a hyphen in all contexts.
o actor-singer
o city-state
o mother-daughter relationship
o parent-teacher conference
✵ ▪ For a compound composed of directional words, use a closed compound when the term describes a single direction. Use a hyphen if the compound consists of coordinated nouns that could be joined with and or by.
o northeast
o southwest
o a street running north-south
o east-southeast winds
✵ ▪ Compounds that identify family relationships vary in whether they are closed up or hyphenated. When in doubt, consult your dictionary. (For the plural and possessive forms of in-law compounds, see 20.1.2 and 20.2.2, respectively.)
o grandfather
o stepdaughter
o step-grandmother
o great-grandmother
o son-in-law
✵ ▪ Some familiar phrases are always hyphenated.
o stick-in-the-mud
o jack-of-all-trades
20.3.2.1 COMPOUNDS INCLUDING PROPER NOUNS. Leave open most compounds that include proper nouns, including names of ethnic groups.
Adjective before noun |
Noun, or adjective after noun |
✵ African American culture |
✵ an African American has written |
✵ French Canadian explorer |
✵ the explorer was French Canadian |
✵ Middle Eastern geography |
✵ the geography of the Middle East |
✵ State Department employees |
✵ employed by the State Department |
✵ Korean War veterans |
✵ veterans of the Korean War |
If, however, the first term is shortened, use a hyphen.
✵ Indo-European languages
✵ origins that were Indo-European
If coordinated terms could be joined by and, hyphenate them.
✵ Israel-Egypt peace treaty
✵ Spanish-English dictionary
20.3.2.2 COMPOUNDS INCLUDING NUMBERS. If a compound includes a number, hyphenate it if it precedes a noun that it modifies; otherwise leave it open. (For the use of numerals versus spelled-out numbers, see chapter 23.)
Adjective before noun |
Noun, or adjective after noun |
✵ fifty-year project |
✵ the project took fifty years |
✵ twenty-one-year-old student |
✵ the student was twenty-one years old |
✵ twentieth-century literature |
✵ studied the literature of the twentieth century |
✵ third-floor apartment |
✵ she lived on the third floor |
✵ 214-day standoff |
✵ standoff that lasted 214 days |
There are a few exceptions:
✵ ▪ Always hyphenate an age term used as a noun.
o a twenty-one-year-old
o three six-year-olds
✵ ▪ Always leave open a compound including the word percent, and give the number in arabic numerals (see 23.1.3).
o a 15 percent increase
o increased by 15 percent
✵ ▪ Always use a hyphen to spell a fraction with words. (See 23.1.3 for use of numerals versus spelled-out numbers in fractions.)
o a two-thirds majority
o a majority of two-thirds
✵ ▪ For a fraction beginning with half or quarter, use a hyphen when it precedes a noun that it modifies; otherwise leave it open.
Adjective before noun |
Noun, or adjective after noun |
o a half-hour session |
o after a half hour had passed |
o a quarter-mile run |
o ran a quarter mile |
✵ ▪ When the second part of a hyphenated expression is omitted, the suspended hyphen is retained, followed by a space (or, in a series, by a comma). But if the compounds are joined by to (as in a span of numbers), hyphenate the whole expression.
o fifteen- and twenty-year mortgages
o five-, ten-, and twenty-dollar bills
o but
o a three-to-five-year gap (a single range)
20.3.3 Words Formed with Prefixes
Words formed with prefixes are normally closed, whether they are nouns (postmodernism), verbs (misrepresent), adjectives (antebellum), or adverbs (prematurely). Use a hyphen, however, in these cases:
✵ ▪ when the prefix is combined with a capitalized word
o sub-Saharan |
o but |
o subdivision |
o pro-Asian |
o but |
o pronuclear |
✵ ▪ when the prefix is combined with a numeral
o pre-1950 |
o but |
o predisposed |
o mid-80s |
o but |
o midlife |
✵ ▪ to separate two i’s, two a’s, or other combinations of letters or syllables that might cause misreading
o anti-intellectual |
o but |
o antidepressant |
o intra-arterial |
o but |
o intramural |
✵ ▪ when the prefix precedes a compound word that is hyphenated or open
o non-coffee-drinking |
o but |
o nonbelief |
o post-high school |
o but |
o postgame |
✵ ▪ to separate repeated terms in a double prefix
o sub-subentry
✵ ▪ when a prefix stands alone
o pre- and postwar
o macro- and microeconomics
These patterns apply to words formed with the following prefixes, among others.
✵ 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 |
Where two prefixes apply to the same word, use a hyphen followed by a space for the first prefix.
✵ over- and underused