The tilde (/ˈtɪld, -di, -də, -deɪ/)^[1] ˜ or ~, is a grapheme with a number of uses. The name of the character came into English from Spanish, which in turn came from the Latin titulus, meaning 'title' or 'superscription'.^[2][a] Its primary use is as a diacritic (accent) in combination with a base letter; but, for historical reasons, it is also used in standalone form within a variety of contexts.

History

Use by medieval scribes

The tilde was originally written over an omitted letter or several letters as a scribal abbreviation, or "mark of suspension" and "mark of contraction",^[3] shown as a straight line when used with capitals. Thus, the commonly used words Anno Domini were frequently abbreviated to A^o Dñi, with an elevated terminal with a suspension mark placed over the "n". Such a mark could denote the omission of one letter or several letters. This saved on the expense of the scribe's labor and the cost of vellum and ink. Medieval European charters written in Latin are largely made up of such abbreviated words with suspension marks and other abbreviations; only uncommon words were given in full.

The text of the Domesday Book of 1086, relating for example, to the manor of Molland in Devon (see adjacent picture), is highly abbreviated as indicated by numerous tildes.

The text with abbreviations expanded is as follows:

Mollande tempore regis Edwardi geldabat pro quattuor hidis et uno ferling. Terra est quadraginta carucae. In dominio sunt tres carucae et decem servi et triginta villani et viginti bordarii cum sedecim carucis. Ibi duodecim acrae prati et quindecim acrae silvae. Pastura tres leugae in longitudine et latitudine. Reddit quattuor et viginti libras ad pensam. Huic manerio est adjuncta Blachepole. Elwardus tenebat tempore regis Edwardi pro manerio et geldabat pro dimidia hida. Terra est duae carucae. Ibi sunt quinque villani cum uno servo. Valet viginti solidos ad pensam et arsuram. Eidem manerio est injuste adjuncta Nimete et valet quindecim solidos. Ipsi manerio pertinet tercius denarius de Hundredis Nortmoltone et Badentone et Brantone et tercium animal pasturae morarum.

Role of mechanical typewriters

On typewriters designed for languages that routinely use diacritics (accent marks), there are two possible solutions. Keys can be dedicated to precomposed characters or alternatively a dead key mechanism can be provided. With the latter, a mark is made when a dead key is typed, but unlike normal keys, the paper carriage does not move on and thus the next letter to be typed is printed under that accent. Typewriters for Spanish typically have a dedicated key for Ñ/ñ but, as Portuguese uses Ã/ã and Õ/õ, a single dead-key (rather than take two keys to dedicate) is the most practical solution.

The tilde symbol did not exist independently as a movable type or hot-lead printing character since the type cases for Spanish or Portuguese would include sorts for the accented forms.

The centralized ASCII tilde

The first ASCII standard (X3.64-1963) did not have a tilde.^[4]: 246 Like Portuguese and Spanish, the French, German and Scandinavian languages also needed symbols in excess of the basic 26 needed for English. The ASA worked with and through the CCITT to internationalize the code-set, to meet the basic needs of at least the Western European languages.

It appears to have been at their May 13–15, 1963 meeting that the CCITT decided that the proposed ISO 7-bit code standard would be suitable for their needs if a lower case alphabet and five diacritical marks were added to it.^[5] At the October 29–31 meeting, then, the ISO subcommittee altered the ISO draft to meet the CCITT requirements, replacing the up-arrow and left-arrow with diacriticals, adding diacritical meanings to the apostrophe and quotation mark, and making the number sign a dual^[b] for the tilde.^[6]

— Yucca's free information site (which cites the original sources).^[7]

Thus ISO 646 was born (and the ASCII standard updated to X3.64-1967), providing the tilde and other symbols as optional characters.^{[4]: 247 [c]}

ISO 646 and ASCII incorporated many of the overprinting lower-case diacritics from typewriters, including tilde. Overprinting was intended to work by putting a backspace code between the codes for letter and diacritic.^[8] However even at that time, mechanisms that could do this or any other overprinting were not widely available, did not work for capital letters, and were impossible on video displays, with the result that this concept failed to gain significant acceptance. Consequently, many of these free-standing diacritics (and the underscore) were quickly reused by software as additional syntax, basically becoming new types of syntactic symbols that a programming language could use. As this usage became predominant, type design gradually evolved so these diacritic characters became larger and more vertically centered, making them useless as overprinted diacritics but much easier to read as free-standing characters that had come to be used for entirely different and novel purposes. Most modern fonts align the plain ASCII "spacing" (free-standing) tilde at the same level as dashes, or only slightly higher.

The free-standing tilde is at code 126 in ASCII, where it was inherited into Unicode as U+007E.

A similar shaped mark (⁓) is known in typography and lexicography as a swung dash: these are used in dictionaries to indicate the omission of the entry word.^[9]

Connection to Spanish

As indicated by the etymological origin of the word "tilde" in English, this symbol has been closely associated with the Spanish language. The connection stems from the use of the tilde above the letter ⟨n⟩ to form the (different) letter ⟨ñ⟩ in Spanish, a feature shared by only a few other languages, most of which are historically connected to Spanish. This peculiarity can help non-native speakers quickly identify a text as being written in Spanish with little chance of error. Particularly during the 1990s, Spanish-speaking intellectuals and news outlets demonstrated support for the language and the culture by defending this letter against globalisation and computerisation trends that threatened to remove it from keyboards and other standardised products and codes.^[10][11] The Instituto Cervantes, founded by Spain's government to promote the Spanish language internationally, chose as its logo a highly stylised Ñ with a large tilde. The 24-hour news channel CNN in the US later adopted a similar strategy on its existing logo for the launch of its Spanish-language version, therefore being written as CN͠N. And similarly to the National Basketball Association (NBA), the Spain men's national basketball team is nicknamed "ÑBA".

In Spanish itself the word tilde is used more generally for diacritics, including the stress-marking acute accent.^[12] The diacritic ~ is more commonly called virgulilla or la tilde de la eñe, and is not considered an accent mark in Spanish, but rather simply a part of the letter ñ (much like the dot over ı makes an i character that is familiar to readers of English).

Usage

Letters with tilde

Unicode encodes a number of cases of "letter with tilde" as precomposed characters and these are displayed below. In addition, many more symbols may be composed using the combining character facility (U+0303 ◌̃ COMBINING TILDE, U+0330 ◌̰ COMBINING TILDE BELOW and others) that may be used with any letter or other diacritic to create a customised symbol but this does not mean that the result has any real-world application and are not shown in the table.

A tilde diacritic can be added to almost any character by using a combining tilde. Greek and Cyrillic letters with tilde (Α͂ ᾶ, Η͂ ῆ, Ι͂ ῖ, ῗ, Υ͂ ῦ, ῧ and А̃ а̃, Ә̃ ә̃, Е̃ е̃, И̃ и̃, О̃ о̃, У̃ у̃, Ј̃ j̃) are formed using this method.

Common use in English

The English language does not use the tilde as a diacritic, though it is used in some loanwords. The standalone form of the symbol is used more widely. Informally,^[13] it means "approximately", "about", or "around", such as "~30 minutes before", meaning "approximately 30 minutes before".^[14][15] It may also mean "similar to",^[16] including "of the same order of magnitude as",^[13] such as "x ~ y" meaning that x and y are of the same order of magnitude. Another approximation symbol is the double tilde ≈, meaning "approximately/almost equal to".^[14][16][17] The tilde is also used to indicate congruence of shapes by placing it over an = symbol, thus ≅.

In more recent digital usage, tildes on either side of a word or phrase have sometimes come to convey a particular tone that "let the enclosed words perform both sincerity and irony", which can pre-emptively defuse a negative reaction.^[18] For example, BuzzFeed journalist Joseph Bernstein interprets the tildes in the following tweet:

"in the ~ spirit of the season ~ will now link to some of the (imho) #Bestof2014 sports reads. if you hate nice things, mute that hashtag."

as a way of making it clear that both the author and reader are aware that the enclosed phrase – "spirit of the season" – "is cliche and we know this quality is beneath our author, and we don't want you to think our author is a cliche person generally".^[18][d]

Among other uses, the symbol has been used on social media to indicate sarcasm.^[19] It may also be used online, especially in informal writing such as fanfiction, to convey a cutesy, playful, or flirtatious tone.^[20]

Diacritical use

In some languages, the tilde is a diacritic mark placed over a letter to indicate a change in its pronunciation:

Pitch

The tilde was firstly used in the polytonic orthography of Ancient Greek, as a variant of the circumflex, representing a rise in pitch followed by a return to standard pitch.

Abbreviation

Later, it was used to make abbreviations in medieval Latin documents. When an ⟨n⟩ or ⟨m⟩ followed a vowel, it was often omitted, and a tilde (physically, a small ⟨N⟩) was placed over the preceding vowel to indicate the missing letter; this is the origin of the use of tilde to indicate nasalization (compare the development of the umlaut as an abbreviation of ⟨e⟩.) The practice of using the tilde over a vowel to indicate omission of an ⟨n⟩ or ⟨m⟩ continued in printed books in French as a means of reducing text length until the 17th century. It was also used in Portuguese and Spanish.

The tilde was also used occasionally to make other abbreviations, such as over the letter ⟨q⟩, making q̃, to signify the word que ("that").

Nasalization

It is also as a small ⟨n⟩ that the tilde originated when written above other letters, marking a Latin ⟨n⟩ which had been elided in old Galician-Portuguese. In modern Portuguese it indicates nasalization of the base vowel: mão "hand", from Lat. manu-; razões "reasons", from Lat. rationes. This usage has been adopted in the orthographies of several native languages of South America, such as Guarani and Nheengatu, as well as in the International Phonetic Alphabet (IPA) and many other phonetic alphabets. For example, is the IPA transcription of the pronunciation of the French place-name Lyon.

In Breton, the symbol ⟨ñ⟩ after a vowel means that the letter ⟨n⟩ serves only to give the vowel a nasalised pronunciation, without being itself pronounced, as it normally is. For example, ⟨an⟩ gives the pronunciation whereas ⟨añ⟩ gives .

In the DMG romanization of Tunisian Arabic, the tilde is used for nasal vowels õ and ṏ.

Palatal n

The tilded ⟨n⟩ (⟨ñ⟩, ⟨Ñ⟩) developed from the digraph ⟨nn⟩ in Spanish. In this language, ⟨ñ⟩ is considered a separate letter called eñe (IPA: [ˈeɲe]), rather than a letter-diacritic combination; it is placed in Spanish dictionaries between the letters ⟨n⟩ and ⟨o⟩. In Spanish, the word tilde actually refers to diacritics in general, e.g. the acute accent in José,^[21] while the diacritic in ⟨ñ⟩ is called "virgulilla" (IPA: [birɣuˈliʝa]) (yeísta) or (IPA: [birɣuˈliʎa]) (non-yeísta). ^[22] Current languages in which the tilded ⟨n⟩ (⟨ñ⟩) is used for the palatal nasal consonant /ɲ/ include

Tone

In Vietnamese, a tilde over a vowel represents a creaky rising tone (ngã). Letters with the tilde are not considered separate letters of the Vietnamese alphabet.

International Phonetic Alphabet

In phonetics, a tilde is used as a diacritic that is placed above a letter, below it or superimposed onto the middle of it:

• A tilde above a letter indicates nasalization, e.g. , ṽ.
• A tilde superimposed onto the middle of a letter indicates velarization or pharyngealization, e.g. ɫ, z̴. If no precomposed Unicode character exists, the Unicode character U+0334 ◌̴ COMBINING TILDE OVERLAY can be used to generate one.
• A tilde below a letter indicates laryngealisation, e.g. d̰. If no precomposed Unicode character exists, the Unicode character U+0330 ◌̰ COMBINING TILDE BELOW can be used to generate one.

Letter extensionedit

In Estonian, the symbol ⟨õ⟩ stands for the close-mid back unrounded vowel, and it is considered an independent letter.

Other usesedit

Some languages and alphabets use the tilde for other purposes, such as:

• Arabic script: A symbol resembling the tilde (U+0653 ـٓ ARABIC MADDAH ABOVE) is used over the letter ⟨ا⟩ (/a/) to become ⟨آ⟩, denoting a long /ʔaː/ sound.
• Guaraní: The tilded ⟨G̃⟩ (note that ⟨G/g⟩ with tilde is not available as a precomposed glyph in Unicode) stands for the velar nasal consonant. Also, the tilded ⟨y⟩ (⟨Ỹ⟩) stands for the nasalized upper central rounded vowel ɨ̃. Munduruku, Parintintín, and two older spellings of Filipino words also use ⟨g̃⟩.
• Syriac script: A tilde (~) under the letter Kaph represents a t͡ʃ sound, transliterated as ch or č.^[23]
• Estonian and Võro use the tilde above the letter o (õ) to indicate the vowel ɤ, a rare sound among languages.
• Unicode has a combining vertical tilde character: U+033E ◌̾ COMBINING VERTICAL TILDE. It is used to indicate middle tone in linguistic transcription of certain dialects of the Lithuanian language.^[24]
• Resurrección María de Azkue's 1906 Basque dictionary used an idiosyncratic spelling including ⟨ã d̃ ẽ ĩ l̃ ñ õ s̃ t̃ ũ x̃⟩.^[25]

Punctuationedit

The tilde is used in various ways in punctuation, such as:

Rangeedit

In some languages (though not generally in English), a tilde or a tilde-like wave dash (Unicode: U+301C 〜 WAVE DASH) may be used as a punctuation mark (instead of an unspaced hyphen, en dash or em dash) between two numbers, to indicate a range. Doing so avoids the risk of confusion with subtraction or a hyphenated number (such as a part number or model number). For example, "12~15" means "12 to 15", "~3" means "up to three", and "100~" means "100 and greater".^{[citation needed]} East Asian languages almost always use this convention, but it is sometimes done for clarity in some other languages as well. Chinese uses the wave dash and full-width em dash interchangeably for this purpose. In English, the tilde is often used to express ranges and model numbers in electronics, but rarely in formal grammar or in type-set documents, as a wavy dash preceding a number sometimes represents an approximation (see below).

Approximationedit

Before a number the tilde can mean 'approximately'; '~42' means 'approximately 42'.^[26] When used with currency symbols that precede the number (national conventions differ), the tilde precedes the symbol, thus for example '~$10' means 'about ten dollars'.^{[27][better source needed]}

The symbols ≈ (almost equal to) and ≅ (approximately equal to) are among the other symbols used to express approximation.

Japaneseedit

The wave dash (波ダッシュ, nami dasshu) is used for various purposes in Japanese, including to denote ranges of numbers (e.g., 5〜10 means between 5 and 10) in place of dashes or brackets, and to indicate origin. The wave dash is also used to separate a title and a subtitle in the same line, as a colon is used in English.

When used in conversations via email or instant messenger it may be used as a sarcasm mark ^{[citation needed]}.

The sign is used as a replacement for the chōon, katakana character, in Japanese, extending the final syllable.

Unicode and Shift JIS encoding of wave dashedit

Correct JIS wave dash, current in Unicode

Previous Unicode wave dash (incorrect)

In practice the full-width tilde (全角チルダ, zenkaku chiruda) (Unicode U+FF5E ～ FULLWIDTH TILDE), is often used instead of the wave dash (波ダッシュ, nami dasshu) (Unicode U+301C 〜 WAVE DASH), because the Shift JIS code for the wave dash, 0x8160, which should be mapped to U+301C,^[28][29] is instead mapped to U+FF5E^[30] in Windows code page 932 (Microsoft's code page for Japanese), a widely used extension of Shift JIS.

This decision avoided a shape definition error in the original (6.2) Unicode code charts:^[31] the wave dash reference glyph in JIS / Shift JIS^[32][33] matches the Unicode reference glyph for U+FF5E FULLWIDTH TILDE,^[34] while the original reference glyph for U+301C^[31] was reflected, incorrectly,^[35] when Unicode imported the JIS wave dash. In other platforms such as the classic Mac OS and macOS, 0x8160 is correctly mapped to U+301C. It is generally difficult, if not impossible, for users of Japanese Windows to type U+301C, especially in legacy, non-Unicode applications.

A similar situation exists regarding the Korean KS X 1001 character set, in which Microsoft maps the EUC-KR or UHC code for the wave dash (0xA1AD) to U+223C ∼ TILDE OPERATOR,^[36][37] while IBM and Apple map it to U+301C.^[38][39][40] Microsoft also uses U+FF5E to map the KS X 1001 raised tilde (0xA2A6),^[37] while Apple uses U+02DC ˜ SMALL TILDE.^[40]

The current Unicode reference glyph for U+301C has been corrected^[35] to match the JIS standard^[41] in response to a 2014 proposal, which noted that while the existing Unicode reference glyph had been matched by fonts from the discontinued Windows XP, all other major platforms including later versions of Microsoft Windows shipped with fonts matching the JIS reference glyph for U+301C.^[42]

The JIS / Shift JIS wave dash is still formally mapped to U+301C as of JIS X 0213,^[43] whereas the WHATWG Encoding Standard used by HTML5 follows Microsoft in mapping 0x8160 to U+FF5E.^[44] These two code points have a similar or identical glyph in several fonts, reducing the confusion and incompatibility.

Mathematicsedit

As a unary operatoredit

A tilde in front of a single quantity can mean "approximately", "about"^[14] or "of the same order of magnitude as."

In written mathematical logic, the tilde represents negation: "~p" means "not p", where "p" is a proposition. Modern use often replaces the tilde with the negation symbol (¬) for this purpose, to avoid confusion with equivalence relations.

As a relational operatoredit

In mathematics, the tilde operator (which can be represented by a tilde or the dedicated character U+223C ∼ TILDE OPERATOR), sometimes called "twiddle", is often used to denote an equivalence relation between two objects. Thus "x ~ y" means "x is equivalent to y". It is a weaker statement than stating that x equals y. The expression "x ~ y" is sometimes read aloud as "x twiddles y", perhaps as an analogue to the verbal expression of "x = y".^[45]

The tilde can indicate approximate equality in a variety of ways. It can be used to denote the asymptotic equality of two functions. For example, f (x) ~ g(x) means that ${\displaystyle \lim _{x\to \infty }{\frac {f(x)}{g(x)}}=1}$.^[13]

A tilde is also used to indicate "approximately equal to" (e.g. 1.902 ~= 2). This usage probably developed as a typed alternative to the libra symbol used for the same purpose in written mathematics, which is an equal sign with the upper bar replaced by a bar with an upward hump, bump, or loop in the middle (︍︍♎︎) or, sometimes, a tilde (≃). The symbol "≈" is also used for this purpose.

In physics and astronomy, a tilde can be used between two expressions (e.g. h ~ 10⁻³⁴ J s) to state that the two are of the same order of magnitude.^[13]

In statistics and probability theory, the tilde means "is distributed as";^[13] see random variable(e.g. X ~ B(n,p) for a binomial distribution).

A tilde can also be used to represent geometric similarity (e.g. ∆ABC ~ ∆DEF, meaning triangle ABC is similar to DEF). A triple tilde (≋) is often used to show congruence, an equivalence relation in geometry.

In graph theory, the tilde can be used to represent adjacency between vertices. The edge ${\displaystyle (x,y)}$ connects vertices ${\displaystyle x}$ and ${\displaystyle y}$ which can be said to be adjacent, and this adjacency can be denoted ${\displaystyle x\sim y}$.

As a diacriticedit

The symbol "${\displaystyle {\tilde {f}}}$" is pronounced as "eff tilde" or, informally, as "eff twiddle".^[46][47] This can be used to denote the Fourier transform of f, or a lift of f, and can have a variety of other meanings depending on the context.

A tilde placed below a letter in mathematics can represent a vector quantity (e.g. ${\displaystyle (x_{1},x_{2},x_{3},\ldots ,x_{n})={\underset {^{\sim }}{\mathbf {x} }}}$).

In statistics and probability theory, a tilde placed on top of a variable is sometimes used to represent the median of that variable; thus ${\displaystyle {\tilde {\mathbf {y} }}}$ would indicate the median of the variable ${\displaystyle \mathbf {y} }$. A tilde over the letter n (${\displaystyle {\tilde {n}}}$) is sometimes used to indicate the harmonic mean.

In machine learning, a tilde may represent a candidate value for a cell state in GRUs or LSTM units. (e.g. c̃)

Physicsedit

Often in physics, one can consider an equilibrium solution to an equation, and then a perturbation to that equilibrium. For the variables in the original equation (for instance ${\displaystyle X}$) a substitution ${\displaystyle X\to x+{\tilde {x}}}$ can be made, where ${\displaystyle x}$ is the equilibrium part and ${\displaystyle {\tilde {x}}}$ is the perturbed part.

A tilde is also used in particle physics to denote the hypothetical supersymmetric partner. For example, an electron is referred to by the letter e, and its superpartner the selectron is written ẽ.

In multibody mechanics, the tilde operator maps three-dimensional vectors ${\displaystyle {\boldsymbol {\omega }}\in \mathbb {R} ^{3}}$ to skew-symmetrical matrices Zdroj:https://en.wikipedia.org?pojem=Ṽ
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