The hyphen ( ‐ ) is a punctuation mark used to join words and to separate syllables of a single word. It is often confused with dashes ( –, —, ― ), which are longer and have different uses, and with the minus sign ( − ) which is also longer. The use of hyphens is called hyphenation. In environments that are restricted to ISO 646 the Hyphen-minus is used as a replacement.
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 past have been hyphenated (e.g. "toolbar", "hyperlink", "pastebin").
Despite decreased usage, 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).
To allow more efficient usage of paper, more regular appearance of right-side margins without requiring spacing adjustments, and to eliminate the need to erase hand-written long words begun near the end of a line that do not fit, words may be divided at the nearest breakpoint between syllables and a hyphen inserted to indicate that the letters form a word fragment, not a word. For example:
|Without hyphenation||With hyphenation|
We, therefore, the
We, therefore, the represen-
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.
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 tends towards omission of the hyphen (preschool). A hyphen is mandatory 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.
Hyphens are occasionally used to denote syllabification, as in syl-la-bi-fi-ca-tion. Most 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".
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 real-world example. Without the hyphen, there is potential confusion about whether American applies to football or player, or whether the author might perhaps be referring to a "world example" that is "real". 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, high school students, not high-school students. Although the sentence is technically ambiguous, it would normally be formulated differently if another meaning were intended. Noun–noun compound modifiers are also written 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.
Hyphens should normally not be used in adverb–adjective modifiers such as wholly owned subsidiary and quickly moving vehicle, because the adverbs clearly modify the adjectives; "quickly" cannot modify "vehicle". However, if the adverb can also function as an adjective, then a hyphen may be used for clarity. 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, "a more-important reason" is not correct, since it is semantically indistinct from the (correct) "a more important reason".) A mass-noun example is the following: more-beautiful scenery as distinct from more beautiful scenery. Other examples are well-received speech and hard-won fight.
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.
An en dash ( – ) sometimes replaces the hyphen in hyphenated compounds if either of its constituent parts is already hyphenated or contains a space (e.g. high-priority–high-pressure tasks (tasks which are both high-priority and high-pressure). 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.
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.
Two-word names of numbers less than one hundred are hyphenated. For instance, the number 23 should be written twenty-three, and 123 should be written one hundred and twenty-three. (The word and is omitted in American English.)
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.
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"), common in German, 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).
A hyphen may be used to connect groups of numbers, such as in dates (see below), telephone numbers or sports scores.
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”).
Some strong examples of semantic changes caused by the placement of hyphens:
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 the ASCII character encoding, the hyphen was encoded as character 45. Technically, this character is called the hyphen-minus, as it is also used as the minus sign and for dashes. In Unicode, this same character 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 a series of dashes. Use of the hyphen-minus character is discouraged where possible, in favour of the specific hyphen character. Nevertheless, since the Unicode hyphen is awkward to enter on normal keyboards, the hyphen-minus character remains extremely common. Hyphens 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 hyphens (--) to represent a dash in ASCII text.
When flowing text, a system may consider the soft hyphen to be a point at which a word may be broken, and display a hyphen at the end of the broken line; if the line is not broken at that point, the hyphen is not displayed. In most parts of ISO-8859 the soft hyphen is at position 0xAD, and since the first 256 positions in Unicode are taken from ISO-8859-1, it has a Unicode codepoint of U+00AD. HTML 3.2 introduced a character entity for the soft hyphen, '
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 or Romanian s‑a 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 is not treated as a word boundary.
The ASCII hyphen-minus character is also often used when specifying parameters to programs in a command line interface. The character is usually followed by one or more letters that indicate specific actions. Typically it is called a dash in this context. This is used in many different operating systems, particularly Unix and Unix-like systems. DOS and Microsoft Windows also sometimes make use of the hyphen, although the use of a forward slash (/) is more prevalent there. 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 action names are used. This is a common feature of GNU software.
Continental Europeans use the hyphen 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. Usage 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 method has gained influence within North America, as most common computer filesystems make the use of slashes difficult or impossible. Windows uses both \ and / as the directory separator, and / is also used to introduce and separate switches to shell commands. 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. The non-year form is also identical apart from the separator used 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 name||BRAILLE PATTERN DOTS-36|
Invented by Louis Braille, six-dot Braille cells have a grid of two dots horizontally by three dots vertically. The dots are conventionally numbered 1, 2, and 3 from the top of the left column and 4, 5, and 6 from the top of the right column.