Hyphen

This article is about the punctuation mark. For other uses, see Hyphen (disambiguation).

The hyphen ( ‐ ) is a punctuation mark used to join words and to separate syllables of a single word. The use of hyphens is called hyphenation. The hyphen should not be confused with dashes ( ‒, –, —, ― ), which are longer and have different uses, or with the minus sign ( − ) which is also longer. However, in environments that are restricted to ISO 646, and often in computing generally, the hyphen is represented by a hyphen-minus ( - ), which is well-known and easy to enter on keyboards.

Usage in English

Hyphens are mostly used to break single words into parts, or to join ordinarily separate words into single words. Spaces should not be placed between a hyphen and either of the words it connects except when using a suspended or "hanging" hyphen (e.g. nineteenth- and twentieth‑century writers).

A definitive collection of hyphenation rules does not exist; rather, different manuals of style prescribe different usage guidelines. The rules of style that apply to dashes and hyphens have evolved to support ease of reading in complex constructions; editors often accept deviations from them that will support, rather than hinder, ease of reading.

The use of the hyphen in English compound nouns and verbs has, in general, been steadily declining. Compounds that might once have been hyphenated are increasingly left with spaces or are combined into one word. In 2007, the sixth edition of the Shorter Oxford English Dictionary removed the hyphens from 16,000 entries, such as fig-leaf (now fig leaf), pot-belly (now pot belly) and pigeon-hole (now pigeonhole). The advent of the Internet and the increasing prevalence of computer technology have given rise to a subset of common nouns that may in the past have been hyphenated (e.g. "toolbar", "hyperlink", "pastebin").

Despite decreased use, hyphenation remains the norm in certain compound modifier constructions and, amongst some authors, with certain prefixes (see below). Hyphenation is also routinely used to avoid unsightly spacing in justified texts (for example, in newspaper columns).

Separating

Justification and line-wrapping

When flowing text, it is sometimes preferable to break a word in half so that it continues on another line rather than moving the entire word to the next line. The word may be divided at the nearest breakpoint between syllables, and a hyphen inserted to indicate that the letters form a word fragment, rather than a full word. This allows more efficient use of paper, allows more regular appearance of right-side margins without requiring spacing adjustments, reduces the problem of rivers, and avoids the need to erase long words begun near the end of a line that do not fit. This kind of hyphenation is most useful when the width of the column of text is very narrow. For example:

Without hyphenation		With hyphenation
We,       therefore,      the representatives of the United States of America...		We, therefore, the represen- tatives of the United States of America...

The details of doing this properly are complex and language-dependent and can interact with other orthographic and typesetting practices. Hyphenation algorithms, when employed in concert with dictionaries, are sufficient for all but the most formal texts. See also justification.

Prefixes and suffixes

Certain prefixes (co-, pre-, mid-, de-, non-, anti-, etc.) may or may not be hyphenated. Many long-established words, such as preamble and degrade, do not require a hyphen since the prefix is viewed as fully fused. In other cases, usage varies depending on individual or regional preference. British English tends towards hyphenation (pre-school) whereas American English and Australian English tend towards omission of the hyphen (preschool). A hyphen is mandatorynice 47774 kay alol when a prefix is applied to a proper (capitalized) adjective (un-American, de-Stalinisation).

In British English, hyphens may be employed where readers would otherwise be tempted into a mispronunciation (e.g., co-worker is so punctuated partly to prevent the reader's eye being caught automatically by the word cow). The AP Stylebook provides further information on the use of "co-" as a prefix.

Hyphens may be used, in association with prefixes, suffixes or otherwise, when repeated vowels or consonants are pronounced separately rather than being silent or merged in a diphthong. For example: shell-like, anti-intellectual. In the vowel-vowel case, some English authorities use a diaeresis (as in coöperation, rather than co-operation or cooperation), but this style is now rare.

Some prefixed words are hyphenated to distinguish them from other words that would otherwise be homographs, such as recreation (fun or sport) and re‑creation (the act of creating again).

Syllabification and spelling

Hyphens are occasionally used to denote syllabification, as in syl-la-bi-fi-ca-tion. Most British and North American dictionaries use an interpunct, sometimes called a "middle dot" or "hyphenation point", for this purpose, as in syl·la·bi·fi·ca·tion. Similarly, hyphens may be used to indicate a word is being or should be spelled, such as "W-O-R-D spells word".

Joining

Compound modifiers

Compound modifiers 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 American-football player or 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 "celebrated paintings" that are little. Compound modifiers can extend to three or more words, as in ice-cream-flavored candy, and can be adverbial as well as adjectival (spine-tinglingly frightening). However, if the compound is a familiar one, it is usually unhyphenated. For example, at least one style guide prefers the construction high school students, to high-school students. Although the expression is technically ambiguous ("students of a high school" / "school students that are on drugs"), it would normally be formulated differently if the latter meaning were intended. Noun–noun compound modifiers are also written (according to some) without a hyphen when no confusion is likely: grade point average and department store manager.

When a compound adjective follows the term it applies to, a hyphen is typically not used. For example, "that gentleman is well respected", not "that gentleman is well-respected". Some authorities differ, and recommend the hyphen when the compound adjective follows the verb to be or any of its inflections.

According to most style guides, hyphens should not be used in adverb-adjective modifiers when the adverb ends in -ly. For example, wholly owned subsidiary and quickly moving vehicle because the adverbs clearly modify the adjectives and "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. For example, the phrase more-important reasons ("reasons that are more important") is distinguished from more important reasons ("additional important reasons"), where more is an adjective. (In contrast, the hyphen in "a more-important reason" is not necessary to distinguish it from "a more important reason" since both mean the same thing.) A mass-noun example is the following: more-beautiful scenery as distinct from more beautiful scenery. Strunk & White notably does not have a prohibition against hyphen use in compound adjectives ending in -ly. Rather, as with other hyphen usage, the key is "common sense" and writing for clarity. See id.

Hyphens are used to connect numbers and words in forming adjectival phrases (particularly with weights and measures), whether using numerals or words for the numbers, as in 28-year-old woman and twenty-eight-year-old woman or 320-foot wingspan. The same usually holds for abbreviated time units. Hyphens are also used in spelled-out fractions as adjectives (but not as nouns), such as two-thirds majority and one-eighth portion. However, with symbols for SI units—as opposed to the names of these units—both the International Bureau of Weights and Measures and the U.S. National Institute of Standards and Technology recommend use without a hyphen: a 25 kg sphere. When the units are spelled out, this recommendation does not apply: a 25-kilogram sphere, a roll of 35-millimeter film.

In English, an en dash ( – ) 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 or public-school–private-school rivalries. En dashes are more proper than hyphens in ranges (pp. 312–14), relationships (blood–brain barrier) and to convey the sense of "to", as in Boston–Washington race.

Other compounds

Connecting hyphens are used in a large number of miscellaneous compounds, other than modifiers, such as in lily-of-the-valley, cock-a-hoop, clever-clever, tittle-tattle and orang-utan. Usage is often dictated by convention rather than fixed rules, and hyphenation styles may vary between authors; for example, orang-utan is also written as orangutan or orang utan, and lily-of-the-valley may or may not be hyphenated.

Some married couples compose a new surname (sometimes referred to as a double-barrelled name) for their new family by combining their two surnames with a hyphen. Jane Doe and John Smith might become Jane and John Smith-Doe, or Doe-Smith, for instance. In some countries, however, only the woman hyphenates her birth surname, appending her husband's surname.

Suspended hyphens

A suspended hyphen (also referred to as a "hanging hyphen" or "dangling hyphen") may be used when a single base word is used with separate, consecutive, hyphenated words which are connected by "and", "or", or "to". For example, nineteenth-century and twentieth-century may be written as nineteenth- and twentieth-century. This usage is now common in English and specifically recommended in some style guides. Although less common, suspended hyphens are also used in English when the base word comes first, as in "investor-owned and -operated". Usages such as "applied and sociolinguistics" (instead of "applied linguistics and sociolinguistics") are frowned on in English; the Indiana University Style Guide uses this example and says "Do not 'take a shortcut' when the first expression is ordinarily open." (i.e., ordinarily two separate words).

Other uses

A hyphen may be used to connect groups of numbers, such as in dates (see below), telephone numbers or sports scores, but it is more proper to use an en-dash to indicate a range of value.

The hyphen is sometimes used to hide letters in words, as in G-d, although an en-dash can be used as well for stylistic purposes (“G–d”).

Varied meanings

Some strong examples of semantic changes caused by the placement of hyphens:

• Disease-causing poor nutrition, meaning poor nutrition that causes disease
• Disease causing poor nutrition, meaning a disease that causes poor nutrition

• A man-eating shark is a shark that eats humans.
• A man eating shark is a man who is eating shark meat.

• A blue-green sea is a sea whose color is somewhere between blue and green.
• A blue green sea is a contradiction, unless "green" is used contextually to mean something other than a color.

• Three-hundred-year-old trees are an indeterminate number of trees that are 300 years old.
• Three hundred-year-old trees are three trees that are 100 years old.
• Three-hundred year-old trees are 300 trees that are 1 year old.

• Passenger-carrying airplanes are airplanes used to carry passengers.
• Passenger carrying airplanes is a passenger carrying airplanes.

• The fruit-eating bat is a bat that eats fruit.
• The fruit eating bat is a fruit that is eating some bat.

Origin and history

The first use of the hyphen—and its origination—is often credited to Johannes Gutenberg of Mainz, Germany circa 1455 with the publication of his 42-line Bible. Examination of an original copy on vellum (Hubay index #35) in the U. S. Library of Congress shows that Gutenberg's movable type was set justified in a uniform style, 42 equal lines per page.

The Gutenberg printing press required words made up of individual letters of type to be held in place by a surrounding non-printing rigid frame. Gutenberg solved the problem of making each line the same length to fit the frame by inserting a hyphen as the last element at the right side margin. This interrupted the letters in the last word, requiring the remaining letters be carried over to the start of the line below. His hyphen appears throughout the Bible as a short, double line inclined to the right at a 60-degree angle.

In medieval times and the early days of printing, the predecessor of the comma was a slash. As the hyphen ought not to be confused with this, a double-slash was used, this resembling an equals sign tilted like a slash. Writing forms changed with time, and included the full development of the comma, so the hyphen could become one horizontal stroke.

Those dictionaries based on the second edition of the Merriam-Webster dictionary used one small, slightly tilted slash for a hyphen which they added at the end of a line where they broke the word, but used a double-slash, much like the very old symbol, to indicate a hyphen that was actually a part of the phrase but just happened to fall at the end of the line. This double-slash would be used in hyphenated phrases in the middle of the text as well, so that there would be no confusion.

In computing

In the ASCII character encoding, the hyphen is encoded as character 45. This character is actually called the hyphen–minus, and it is also used as the minus sign and for dashes. In Unicode, the hyphen–minus is encoded as U+002D ( - ) so that Unicode remains compatible with ASCII. However, Unicode also encodes the hyphen and minus separately, as U+2010 ( ‐ ) and U+2212 ( − ) respectively, along with the em dash, U+2014 ( — ), en dash U+2013 ( – ) and other related characters. The hyphen-minus is a general-purpose character which attempts to fulfill several roles, and wherever accurate typography is needed, the correct hyphen, minus, or other symbol should be used instead. For example, compare 4+3−2=5 (minus) and 4+3-2=5 (hyphen–minus); in most fonts the hyphen-minus will have neither the correct width, thickness nor vertical position.

However, the Unicode hyphen is awkward to enter on most keyboards, so the hyphen–minus character remains very common. They are often used instead of dashes or minus signs in situations where the proper characters are unavailable (such as ASCII-only text) or difficult to enter, or when the writer is unaware of the distinction. Some writers use two hyphen–minuses (--) to represent a dash in ASCII text.

Since it is difficult for a computer program to automatically make good decisions on when to hyphenate a word at a line break, the concept of a soft hyphen was introduced to allow manual specification of a place where a hyphenated break was allowed without forcing a line break in an inconvenient place if the text was later re-flowed. In contrast, a hyphen that is always displayed and printed is called a hard hyphen (though some use this term to refer to a non-breaking hyphen; see below). Soft hyphens are inserted into the text at the positions where hyphenation may occur. It is a tedious task to insert the soft hyphens by hand, and tools using hyphenation algorithms are available that do this automatically. The upcoming Cascading Style Sheets (CSS) version 3 will provide language-specific hyphenation dictionaries.

Most text systems consider a hyphen to be a word boundary and a valid point at which to break a line when flowing text. However, this is not always desirable behavior, especially when it could lead to ambiguity (such as in the examples given before, where recreation and re‑creation would be indistinguishable), or in languages other than English (e.g. a line break at the hyphen in Irish [an t‑athair] Error: {{Lang}}: text has italic markup (help) or Romanian [s‑a] Error: {{Lang}}: text has italic markup (help) would be undesirable). For this purpose, Unicode also encodes a non-breaking hyphen as U+2011 ( ‑ , coded for by ‑). This character looks identical to the regular hyphen, but it is treated as a letter by word processors, namely that the hyphenated word will not be divided at the hyphen should this fall at what would be the end of a line of text; instead, the whole hyphenated word either will remain in full at the end of the line or will go in full to the beginning of the next line.

The ASCII hyphen–minus character is also often used when specifying command-line options. The character is usually followed by one or more letters that indicate specific actions. Typically it is called a dash or switch in this context. This is used in many different operating systems, particularly Unix-like systems. A parameter by itself that is only a single hyphen without any letters usually means that a program is supposed to handle data coming from the standard input or send data to the standard output. Two hyphen-minus characters ( -- ) are used on some programs to specify "long options" where more descriptive option names are used. This is a common feature of GNU software. DOS, OS/2 and Windows also sometimes make use of the hyphen for this purpose, although the use of a forward slash (/) is more prevalent there.

Usage in date notation

Main article: Date and time notation by country

In parts of Europe, the hyphen is used to delineate parts within a written date. Germans and Slavs also used Roman numerals for the month; 14‑VII‑1789, for example, is one way of writing the first Bastille Day, though this usage is rapidly falling out of favour. Plaques on the wall of the Moscow Kremlin are written this way. Use of hyphens, as opposed to the slashes used in the English language, is specified for international standards.

International standard ISO 8601, which was accepted as European Standard EN 28601 and incorporated into various typographic style guides (e.g., DIN 5008 in Germany), brought about a new standard using the hyphen. Now all official European governmental documents use this. These norms prescribe writing dates using hyphens: 1789-07-14 is the new way of writing the first Bastille Day. This is also the typical date format used in large parts of Eastern Europe and Asia, although sometimes with other separators than the hyphen.

This method has gained influence within North America, as most common computer filesystems make the use of slashes difficult or impossible. DOS, OS/2 and Windows simultaneously support both \ and / as directory separators, but / is also used to introduce and separate switches to shell commands (unless reconfigured to use the hyphen-minus in DOS). Unix-like systems use / as a directory separator and, while \ is legal in filenames, it is awkward to use as the shell uses it as an escape character. Unix also uses a space followed by a hyphen to introduce switches. Apart from the separator used the non-year form of the date format is also identical to the standard American representation.

The ISO date format sorts correctly using a default collation, which can be useful in many computing situations including for filenames, so many computer systems and IT technicians have switched to this method. The government of the Commonwealth of Massachusetts, for example, has switched to this method.

Unicode

Apart from dash and minus sign, Unicode has multiple hyphen characters:

• U+2010 ‐ HYPHEN (‐, ‐)
• U+002D - HYPHEN-MINUS (still not to be confused with U+2212 − MINUS SIGN)
• U+00AD SOFT HYPHEN (­)
• U+2011 ‑ NON-BREAKING HYPHEN
• U+2043 ⁃ HYPHEN BULLET (⁃)

And in non-Latin scripts:

• U+058A ֊ ARMENIAN HYPHEN
• U+1400 ᐀ CANADIAN SYLLABICS HYPHEN
• U+1806 ᠆ MONGOLIAN TODO SOFT HYPHEN

See also

• Dash
• Double hyphen
• Hyphen War
• Papyrological hyphen

External links

• A Grammar Book help for hyphen rules
• Economist Style Guide — Hyphens
• Compound Words: When to Hyphenate
• Jukka Korpela, Soft hyphen (SHY) - a hard problem? (see also his article on word breaking, line breaks, and special characters (including hyphens) in HTML)
• Markus Kuhn, Unicode interpretation of SOFT HYPHEN breaks ISO 8859-1 compatibility. Unicode Technical Committee document L2/03-155R, June 2003.
• Hyphenator.js, Hyphenator.js source code
• hypho-o, hypho-o online soft hyphen insertion tool
• Lyric Hyphenator, Online Hyphenation Tool
• United States Government Printing Office Style Manual 2000 6. COMPOUNDING RULES
• ushuaia.pl, online hyphenator (multilanguage)