The Hyphen
15 rules
Hyphen in Compound Adjectives Before a Noun
When two or more words combine to express a single idea and act as an adjective before the noun they modify, join them with hyphens. This covers a wide range of constructions: number-plus-noun (ten-year period), well-plus-participle (well-known attorney), prepositional phrases used as modifiers (state-of-the-art equipment), noun-plus-participle (mind-boggling, time-consuming), adjective-plus-noun-ed (cold-blooded), adjective-plus-noun (large-scale), noun-plus-noun of equal rank (doctor-patient privilege), and verb-plus-verb phrases (stop-and-go traffic). Percentages are an exception — no hyphen is used (a 30 percent increase). When the compound modifier stretches beyond five or six words, enclose it in quotation marks rather than hyphenating. When a compound modifier contains two choices joined by 'and,' separate them with a comma (a civil, and criminal-defense claim); when joined by 'or,' use a slant (an indoor/outdoor seating area). Repeated words forming a one-thought modifier are hyphenated wherever they occur (a go-go dancer; it is very hush-hush). Words expressing a range, alternate views, or rhyme are hyphenated wherever they occur (a give-and-take relationship). The nonwords uh-huh (yes) and uh-uh (no) are always hyphenated. When type, kind, or sort appears in a compound modifier before the head noun, hyphen through that word as part of the chain — the whole pre-noun unit is one compound adjective. Officer-type job, multiple-choice-type worksheet, written-or-oral-type summary, and affirmative-or-negative-type reply all follow this pattern. Do not leave type, kind, or sort open inside the modifier (officer type job, multiple-choice type worksheet). When or joins words in the modifier, hyphen them as one unit through type (written-or-oral-type summary, not written- or oral-type summary — suspending would imply two separate types). Some reporters leave familiar phrases open in testimony; follow reporter preference when established. When a longer modifier contains an established two-word compound such as blood pressure, oil pressure, or water level, keep the pair open inside the phrase (high blood pressure reading, low oil pressure warning, low water level alarm). Do not chain hyphens through the fixed pair (low-oil-pressure warning, low-water-level alarm). Measurement-plus-warning phrases in testimony often stay open throughout (low pressure warning). See 'No Hyphen for Closely Associated Word Pairs.' When the parse is debatable, follow reporter preference — some reporters hyphenate a strict two-word compound (low-pressure warning) when they read low and pressure as one unit before warning.
Hyphen in Compound Adjectives After a Noun
When a compound adjective follows the noun it modifies and sits after a linking verb (is, are, was, were, seems, becomes), the hyphen is generally dropped. This is the predicate-adjective position, and it is governed by the rule — not by the dictionary. A dictionary entry that shows a compound adjective as hyphenated (full-time, part-time, long-term, short-term) reflects only the direct-adjective (before-noun) form. It does not override the predicate-position rule. So 'a full-time position' takes the hyphen, but 'the position is full time' drops it; 'a short-term contract' takes the hyphen, but 'the contract was short term' drops it. Three categories of compound adjectives keep the hyphen in any position: 1. Adjective-plus-noun-plus-ed compounds (middle-aged, heart-shaped, left-handed, short-handed) 2. Established always-hyphenated compounds (tax-free, price-cutting, up-to-date in any position) 3. Range, rhyme, or repeated-word one-thought modifiers (hush-hush, give-and-take, go-go) Adverb position is separate from predicate-adjective position. When a compound is listed in the dictionary as a hyphenated adverb (for example, full-time, part-time) and appears after an action verb, keep the hyphen: 'he travels full-time,' 'she consults part-time.' Used as a noun or concept ('full time is 40 hours'), no hyphen — the dictionary does not list a noun form for these words.
No Hyphen for Closely Associated Word Pairs
Certain pairs of words have become so closely associated through common usage that they are recognized as compound nouns and do not require hyphens when acting as adjectives before a noun. These include familiar compound terms such as blood vessel disease, chicken pox rash, credit card fraud, high school records, real estate enterprises, safe deposit boxes, and court reporting pursuits. Because the first element is universally understood as part of the compound noun, no hyphen is needed for clarity. The same principle applies to familiar measurement compounds in testimony, such as blood pressure, oil pressure, and water level. When an adjective precedes a fixed pair or a measurement phrase before a head noun, keep the phrase open (high blood pressure reading, low oil pressure warning, low water level alarm, low pressure warning). Do not chain hyphens through the whole phrase (low-oil-pressure warning, low-water-level alarm). Some reporters hyphenate a strict two-word compound such as low-pressure before warning; that is reporter preference when the meaning is clear either way. This rule applies only to established multiple-word compound nouns — it does not apply to ordinary adjective-plus-noun combinations like 'low cost' or 'short term,' which are not recognized compound nouns and should be hyphenated when used as compound modifiers before a noun (low-cost option, short-term plan).
Hyphen in Compound Nouns
Use hyphens between two or more words that combine to form a single idea and function as a noun. These compound nouns name a thing or concept that is distinct from the individual words. Examples include free-for-all, know-how, no-brainer, people-pleaser, switch-hitter, one-upmanship, triple-dippers, and goings-on.
Hyphen in Compound Verbs
Hyphenate two or more verbs that combine to form a single verb (cross-examine, double-dare, recross-examine). Do not hyphenate a verb and a preposition when each word functions independently (crossed off, follow up, sign up). However, when a verb-plus-preposition combination forms a compound noun, hyphenate it (check-in, write-in, pray-ins). Most compound nouns formed from verb-plus-out are written as one word (cookout, handout, dropout). Compound nouns with verb-plus-off or verb-plus-up may be one word or hyphenated — consult a dictionary when uncertain.
Hyphen with Prefixes
Use a hyphen between a prefix and a word that is capitalized, unusual, a number, or capable of being misread (re-charge vs. recharge, re-collect vs. recollect). Common prefixes such as anti, bi, co, counter, de, macro, micro, mid, mini, multi, non, post, pre, pro, semi, and re are generally printed solid. Do not double the letters a or i — insert a hyphen instead (ultra-antagonistic, anti-inflammatories, semi-indirect). Although pre and post are typically attached without a hyphen (pretrial, postdoctoral), Black's Law Dictionary hyphenates expressions like post-trial discovery. Always hyphenate self and quasi. Hyphenate ex and then when they mean 'former' (ex-husband, then-president). When a prefix is added to a compound noun that is already hyphenated or spaced, add a hyphen after the prefix and keep the original compound intact (post-high school, pre-tax-exempt, non-income-producing).
Suspending Hyphen
Use a suspending hyphen when a compound idea has one shared ending but two or more adjective choices preceding it. Retain the hyphen after each suspended element and type one space before any conjunction (and, or). For example: 8-, 18-, or 80-foot boat; three- or four-month waiting period; 6-, 12-, and 18-month notes. The suspended hyphen signals that each preceding element connects to the shared base word. Do not use a suspended hyphen when the speaker describes one category, not parallel alternatives sharing a base. A written-or-oral-type summary is one format; a written- or oral-type summary would parse as written-type or oral-type — a different meaning. When or joins words in a compound modifier that includes type, kind, or sort, hyphen through type as part of one unit (written-or-oral-type summary, affirmative-or-negative-type reply) — not a suspended hyphen before type.
Hyphen with Letters and Numbers
Use a hyphen when letters and numbers combine in specific designations: exhibit labels (Exhibit P-4), aircraft designations (F-16, B-52s, DC-10s), military rank codes (E-5, E-7), some medical terminology (DSM-III-R, C5-C6), and musical keys followed by flat, natural, or sharp (A-sharp, E-flat — but F minor, with no hyphen for minor or major). Hyphenate the letters of words that are spelled out (F-o-r-d-h-a-m). Use a hyphen when a single letter acts as an adjective, prefix, or part of a verb (U-turn, A-line, T-intersection, L-shaped). Some numerical expressions are traditionally hyphenated when spelled out (9-1-1). A lowercased letter sometimes represents a shortened word and is hyphenated to the noun it modifies (b-ball, c-sections, e-mail).
Hyphen in Spelled-Out Numbers and Fractions
Figures from twenty-one through ninety-nine are hyphenated when spelled out, such as at the beginning of a sentence. Fractions that are spelled out are also hyphenated (one-half, two-thirds). If the fraction is expressed with the word 'a' in front of it, do not use a hyphen (a half hour) unless the phrase is a compound modifier before a noun (a half-hour delay). When the expression 'odd' or 'some-odd' appears within a vague number, use a hyphen (20-odd pages, 30 some-odd years). If 'some' comes before the numerical expression, no hyphen is used (some eighty dollars); if 'some' comes between or after the number, hyphenate (eighty-some dollars).
No Hyphen in Civil or Military Titles
Do not use hyphens in civil or military titles that denote a single office or rank (vice president, editor in chief, chief of police, lieutenant governor). These are established compound titles treated as one unit. However, if a prefix or suffix is added to such a title, hyphens are introduced throughout (ex-vice-president, vice-president-elect).
No Hyphen After -ly Adverbs or More/Most/Less
Do not use a hyphen between an adverb ending in -ly and a participle (newly completed, professionally oriented, wholly owned). The test: remove the participle — if what remains makes no sense on its own, the -ly word is an adverb and no hyphen is needed. If the sentence still makes sense, the -ly word is an adjective and a hyphen is required (worldly-minded, homely-faced, family-oriented). Do not use a hyphen between the adverbs more, most, or less and an adjective (most compelling, more important, less restrictive). However, other superlative or comparative forms of adverbs are hyphenated to participles or adjectives that precede nouns (best-known author, highest-ranking officer), though dictionaries vary on whether some have grown together (bestselling vs. best-selling).
Hyphen with Suffixes: -like, -ish, -wise, -type, and Others
Use a hyphen for the suffix -like when attached to a proper adjective or a word ending in l (Wright-like, bell-like, June-like). For all other words, attach -like without a hyphen (childlike, businesslike). The suffixes -ish, -wise, and -type are generally added without a hyphen (sevenish, largeish, stylish). Use hyphens with -wise to prevent misreading or when added to proper nouns (Sorrow-wise, November-wise, Christmas-wise). When -type is added to a word or phrase and the result functions as an adjective before a noun, hyphenate (computer-type, take-charge-type person). If no noun immediately follows -type, do not hyphenate. The suffixes -long, -proof, -sick, and -wide are generally added without a hyphen (yearlong, childproof, heartsick, statewide). Words ending in -ache, -book, -fold, -house, -room, -shop, -skin, or -work are generally written as one word — consult a dictionary for exceptions.
Hyphen with Foreign Phrases, Proper Nouns, and Family Terms as Modifiers
Do not hyphenate foreign expressions or proper nouns when they modify a noun (ad hoc committee, prima facie evidence). For family terms, hyphenate compounds using 'great' or the phrase 'in-law' (great-grandmother, mother-in-law), but do not hyphenate those using 'grand' or 'step' (grandmother, stepson). Use a hyphen between two nouns showing one person holds more than one function, one thing serves more than one purpose, or two people share a common relationship (attorney-client, doctor-patient, work-study). Use a hyphen between two proper nouns that act as a one-thought modifier. When a hyphen already exists within one of the proper nouns, a dash may be used instead of a second hyphen.
Consult a Dictionary for Hyphen Questions
When in doubt about whether a compound is written as two words, hyphenated, or as one word, consult an unabridged dictionary. Words go through a natural transition: they first appear as two separate words, then are hyphenated as they grow closer, and eventually merge into a single word. This process may take many years or just a few. Because the language is always evolving, a current dictionary is the most reliable authority on the status of any particular compound.
No Hyphen with Percentages as Direct Adjectives
Do not hyphenate percentages when they are used as direct adjectives before a noun. The number and the word 'percent' are already considered to be a unit and do not need a hyphen to tie them together.