Editing Hyphen (section)

==== Compound modifiers ====
{{Further|Compound modifier|English compound#Hyphenated compound modifiers}}

[[Compound modifier]]s are groups of two or more words that jointly modify the meaning of another word. When a compound modifier other than an [[adverb]]–[[adjective]] combination appears ''before'' a term, the compound modifier is often hyphenated to prevent misunderstanding, such as in ''{{nowrap|American-football}} player'' or ''{{nowrap|little-celebrated}} paintings''. Without the hyphen, there is potential confusion about whether the writer means a "player of American football" or an "American player of football" and whether the writer means paintings that are "little celebrated" or "celebrated paintings" that are little.<ref>[[Gary Blake]] and [[Robert W. Bly]], ''The Elements of Technical Writing'', p. 48. [[New York City|New York]]: [[Macmillan Publishers (United States)|Macmillan Publishers]], 1993. {{ISBN|0020130856}}</ref> Compound modifiers can extend to three or more words, as in ''{{nowrap|ice-cream-flavored}} candy'', and can be adverbial as well as adjectival (''{{nowrap|spine-tinglingly}} frightening''). However, if the compound is a familiar one, it is usually unhyphenated. For example, some style guides prefer the construction ''high school students'', to ''{{nowrap|high-school}} students''.<ref>E.g. {{cite web |url= https://www.jhsph.edu/news/style_manual/h.html |title=H |work=Bloomberg School Style Manual |publisher=Johns Hopkins Bloomberg School of Public Health |access-date=9 March 2019}}</ref><ref name="IU Style Guide" /> Although the expression is technically ambiguous ("students of a high school"/"school students who are high"), it would normally be formulated differently if other than the first meaning were intended. Noun–noun compound modifiers may also be written without a hyphen when no confusion is likely: ''grade point average'' and ''department store manager''.<ref name="IU Style Guide" />

When a compound modifier ''follows'' the term to which it applies, a hyphen is typically not used if the compound is a temporary compound. For example, "that gentleman is well respected", not "that gentleman is well-respected"; or "a patient-centered approach was used" but "the approach was patient centered."<ref>{{cite web|url=http://www.uhv.edu/ac/newsletters/writing/grammartip2004.11.30.htm |archive-url=https://web.archive.org/web/20100109235952/http://www.uhv.edu/ac/newsletters/writing/grammartip2004.11.30.htm |url-status = dead|archive-date=9 January 2010 |publisher=UHV |type=Grammar tip |date=2004-11-30 |title=Using Hyphens in Compound Adjectives (and Exceptions to the Rule) |first=John |last=Davis |access-date=2010-01-05}}</ref> But permanent compounds, found as headwords in dictionaries, are treated as invariable, so if they are hyphenated in the cited dictionary, the hyphenation will be used in both attributive and predicative positions. For example, "A cost-effective method was used" and "The method was cost-effective" (''cost-effective'' is a permanent compound that is hyphenated as a headword in various dictionaries). When one of the parts of the modifier is a [[proper noun]] or a [[proper adjective]], there is no hyphen (e.g., "a South American actor").<ref name="Hyphenated Compound Words">{{cite web|url = http://englishplus.com/grammar/00000127.htm|title = Hyphenated Compound Words|access-date = 2014-11-18|website = englishplus.com}}</ref>

When the first modifier in a compound is an adverb ending in ''-ly'' (e.g., "a poorly written novel"), various style guides advise no hyphen.<ref name="Hyphenated Compound Words" />{{additional citation needed|date=January 2016}} However, some do allow for this use. For example, ''[[The Economist]] Style Guide'' advises: "Adverbs do not need to be linked to participles or adjectives by hyphens in simple constructions{{nbsp}}... Less common adverbs, including all those that end ''-ly'', are less likely to need hyphens."<ref name="Economist 12">{{cite book |title=The Economist Style Guide |edition=11th |date=2015 |editor-first=Ann |editor-last=Wroe |location=London / New York |publisher=Profile Books / PublicAffairs |pages=77–78 |quote='''hyphens'''&nbsp;&nbsp; ... 12. Adverbs: Adverbs do not need to be linked to participles or adjectives by hyphens in simple constructions [examples elided]. But if the adverb is one of two words together being used adjectivally, a hyphen may be needed [examples elided]. The hyphen is especially likely to be needed if the adverb is short and common, such as ''ill'', ''little'', ''much'' and ''well''. Less common adverbs, including all those that end ''-ly'', are less likely to need hyphens [example elided].}}</ref> In the 19th century, it was common to hyphenate adverb–adjective modifiers with the adverb ending in ''-ly'' (e.g., "a craftily-constructed chair"). However, this has become rare. For example, ''wholly owned subsidiary'' and ''quickly moving vehicle'' are unambiguous, because the adverbs clearly modify the adjectives: "quickly" cannot modify "vehicle".

However, if an adverb can also function as an adjective, then a hyphen may be or should be used for clarity, depending on the style guide.<ref name="Grammar book" /> For example, the phrase ''{{nowrap|more-important}} reasons'' ("reasons that are more important") is distinguished from ''more important reasons'' ("additional important reasons"), where ''more'' is an adjective. Similarly, ''{{nowrap|more-beautiful}} scenery'' (with a [[mass noun|mass-noun]]) is distinct from ''more beautiful scenery''. (In contrast, the hyphen in "a {{nowrap|more-important}} reason" is not necessary, because the syntax cannot be misinterpreted.) A few short and common words—such as ''well'', ''ill'', ''little'', and ''much''—attract special attention in this category.<ref name="Economist 12" /> The hyphen in "well-[past_participled] noun", such as in "[[Cellular differentiation|well-differentiated cells]]", might reasonably be judged superfluous (the syntax is unlikely to be misinterpreted), yet plenty of style guides call for it. Because ''early'' has both adverbial and adjectival senses, its hyphenation can attract attention; some editors, due to comparison with ''advanced-stage disease'' and ''adult-onset disease'', like the parallelism of ''early-stage disease'' and ''early-onset disease''. Similarly, the hyphen in ''little-celebrated paintings'' clarifies that one is not speaking of little paintings.

Hyphens are usually used to connect numbers and words in modifying phrases. Such is the case when used to describe dimensional measurements of weight, size, and time, under the rationale that, like other compound modifiers, they take hyphens in attributive position (before the modified noun),<ref name="AMA10section8.3.1">{{cite book |last=Iverson |first=Cheryl|title=AMA Manual of Style |edition=10th |publisher=[[Oxford University Press]] |location=Oxford, Oxfordshire |year=2007 |isbn=978-0-19-517633-9 |section=8.3.1 |url=https://archive.org/details/amamanualofstyle0000unse }}</ref> although not in predicative position (after the modified noun). This is applied whether numerals or words are used for the numbers. Thus ''{{nowrap|28-year-old}} woman'' and ''{{nowrap|twenty-eight-year-old}} woman'' or ''{{nowrap|32-foot}} wingspan'' and ''{{nowrap|thirty-two-foot}} wingspan'', but ''the woman is 28 years old'' and ''a wingspan of 32 feet''.{{efn|name=Plural nouns|With numbers, where a plural noun would normally be used in an unhyphenated predicative position, the singular form of the noun is generally used in the hyphenated form used attributively. Thus ''a woman who is 28 years old'' becomes ''a {{nowrap|28-year-old}} woman''. There are occasional exceptions to this general rule, for instance with fractions (''a two-thirds majority'') and irregular plurals (''a two-criteria review'', ''a two-teeth bridge'').}} However, with symbols for [[SI]] units (such as ''[[metre|m]]'' or ''[[kilogram|kg]]'')—in contrast to the ''names'' of these units (such as ''[[metre]]'' or ''[[kilogram]]'')—the numerical value is always separated from it with a space: ''a 25&nbsp;kg sphere''. When the unit names are spelled out, this recommendation does not apply: ''a {{nowrap|25-kilogram}} sphere'', ''a roll of {{nowrap|35-millimetre}} film''.<ref>Bureau international des poids et mesures, [https://www.bipm.org/utils/common/pdf/si-brochure/SI-Brochure-9.pdf#page=151 ''Le Système international d'unités (SI) / The International System of Units (SI)'', 9th ed.] (Sèvres: 2019), {{ISBN|978-92-822-2272-0|invalid1=yes}}, sub§5.4.3, p. 149; [http://physics.nist.gov/cuu/pdf/sp811.pdf "Guide for the Use of the International System of Units (SI)"], NIST Special Publication 811, [[National Institute of Standards and Technology]], March 2008.</ref>

In spelled-out [[fraction (mathematics)|fractions]], hyphens are usually used when the fraction is used as an adjective but not when it is used as a noun: thus ''{{nowrap|two-thirds}} majority''{{efn|name=Plural nouns}} and ''{{nowrap|one-eighth}} portion'' but ''I drank two thirds of the bottle'' or ''I kept three quarters of it for myself''.<ref name="APA6section4.13">{{Citation |author=American Psychological Association (APA) |author-link=American Psychological Association |year=2010 |title=The Publication Manual of the American Psychological Association |edition=6th |publisher=American Psychological Association |location=Washington, DC|isbn=978-1-4338-0562-2 |url=http://apastyle.org/ |postscript=.}}</ref> However, at least one major style guide<ref name="AMA10section8.3.1" /> hyphenates spelled-out fractions invariably (whether adjective or noun).

In English, {{Anchor|En dash, hyphen, or either one}} an [[en dash]], {{char|–}}, sometimes replaces the hyphen in hyphenated compounds if either of its constituent parts is already hyphenated or contains a space (for example, ''San Francisco–area residents'', ''hormone receptor–positive cells'', ''cell cycle–related factors'', and ''public-school–private-school rivalries'').<ref name="LutzStevenson2005">{{cite book|author1=Gary Lutz|author2=Diane Stevenson|title=The Writer's Digest grammar desk reference|url=https://books.google.com/books?id=SsQ9ugnMcpUC&pg=PA296|year=2005|publisher=Writer's Digest Books|isbn=978-1-58297-335-7|page=296}}</ref> A commonly used alternative style is the hyphenated string (''hormone-receptor-positive cells'', ''cell-cycle-related factors''). (For other aspects of en dash–versus–hyphen use, see ''[[Dash#En dash|Dash § En dash]]''.)