X

This article is about the letter. For other uses, see X (disambiguation).

X (minuscule: x) is the twenty-fourth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ex (pronounced /ˈɛks/ (listen)), plural exes.

History

Western Greek Chi	Etruscan X	Latin X
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The letter ⟨X⟩, representing /ks/, was inherited from the Etruscan alphabet. It perhaps originated in the ⟨Χ⟩ of the Euboean alphabet or another Western Greek alphabet, which also represented /ks/. Its relationship with the ⟨Χ⟩ of the Eastern Greek alphabets, which represented /kʰ/, is uncertain.

The pronunciation of /ks/ in the Romance languages underwent sound changes, with various outcomes:

• French: /js/ (e.g., laisser from laxare)
• Italian: /ss/ (e.g., asse from axem) and, in some cases, /ʃʃ/ (e.g., lasciare from laxare)
• Portuguese: /jʃ/ (e.g., eixo from axem)
• Romanian: /ps/ (e.g., coapsă from coxa) and /s/ (e.g., lăsa from laxare)
• Old Spanish: /ʃ/
  • Spanish: /x/ (e.g., cuja from coxa)

In Old Spanish, ⟨x⟩ came to represent /ʃ/, which it still represents in most Iberian languages and in the orthographies of other languages influenced by Spanish, such as Nahuatl. In French (with a few exceptions), Italian, Romanian, and modern Spanish, ⟨x⟩ was replaced by other letters.

The use of ⟨x⟩ to represent /ks/ was reintroduced to the Romance languages via Latin loanwords. In many words, the /ks/ was voiced as /gz/.

Use in writing systems

Pronunciation of ⟨x⟩ by language

Orthography	Phonemes	Environment
Asturian	/ʃ/	All environments
	/s/	In between-vowels, only in learned loanwords, can usually be written as s as well
Afar	Template:IPAslink
Albanian	Template:IPAslink
Azeri	Template:IPAslink
Basque	Template:IPAslink
Catalan	/t͡ʃ ~ ʃ/	Usually (word-initially, after consonants)
	/(j)ʃ/	In the digraph ix
	/gz/	In the initial groups ex- and inex- followed by vowel, ⟨h⟩ or a voiced consonant
	/ks/	Between vowels, between a vowel and voiceless consonant and word-finally, after a vowel or consonant
Template:Nwr	Template:IPAslink
Dutch	/ks/	Usually, mainly used in loanwords
	Template:IPAslink	In Texel
English	/ks/	Usually; before an unstressed vowel
	/gz/	Before a stressed vowel
	Template:IPAslink	Word-initially
	Template:IPAslink	In words derived from other languages, especially Spanish and Classical Nahuatl/Nahuatl.
Esperanto	in digraphs only as a substitute for a diacritic	cx, gx, hx, jx, sx, ux are used as substitutes for ĉ, ĝ, ĥ, ĵ, ŝ, ŭ where these characters are not available, see X-convention
French	/ks/	Usually; in Aix- (prefix or name of several places)
	/gz/	Mainly in the prefix ex- followed by a vowel; sometimes word-initially
	Silent	Word-finally with no liaison
	Template:IPAslink	Word-finally with liaison; in sixième (6th) and dixième (10th)
	Template:IPAslink	In six (6), dix (10), Auxerre, and Bruxelles (Brussels)
Galician	Template:IPAslink	Usually
	/(k)s/	Some learned loanwords
German	/ks/	Mainly used in loanwords
Indonesian	Template:IPAslink	In the beginning of a word, mainly used in loanwords for science
	/ks/	In the middle or the end of a word, although words borrowed with the letter x in the middle or the end of a word are almost always replaced by the letters 'ks'. However, the letter x does appear in the middle or the end of certain names.
Italian	/ks/	Mainly used in learned loanwords
Kurdish	Template:IPAslink
Lao romanization	Template:IPAslink	A "low consonant", affects the tone of the following vowel
Leonese	Template:IPAslink
Ligurian	Template:IPAslink
Maltese	Template:IPAslink
Mayan (ALMG)	Template:IPAslink
Nahuatl	Template:IPAslink
Nguni	Template:IPAslink
Norwegian	/ks/	Archaic
Occitan	Template:IPAslink	Usually
	Template:IPAslink	Before consonants
	/ɡz/	In the prefix ex- before vowels in the Provençal, Limousin, Auvergnat, Vivaro-Alpine, and Niçard dialects
	/ɡʒ/	Before ⟨i⟩ and ⟨u⟩ in the Auvergnat dialect
Oromo	Template:IPAslink
Pirahã	Template:IPAslink
Polish	/ks ~ gz/	Unused in Polish orthography, except in loanwords.
Portuguese	Template:IPAslink	Usually, always when word-initially
	/ks/	Found between vowels in some words, mainly in those that entered the language recently
	Template:IPAslink	When preceded by ⟨e⟩ and succeeded by a consonant
	Template:IPAslink	In the prefixes ⟨ex⟩ when before a vowel and ⟨exo⟩
	/gz/	Optionally in the prefix hexa-, although most dialects just pronounce this prefix's ⟨x⟩ as /ks/ or Template:IPAslink
Sardinian	Template:IPAslink
Sicilian	Template:IPAslink	Old Sicilian words and names, e.g. Craxi and Giancaxio
	/k(ə)s(ə)/	Loanwords
Somali	Template:IPAslink
Spanish	/(k)s/	Usually
	Template:IPAslink	Word-initially
	Template:IPAslink, Template:IPAslink, Template:IPAslink	In some names and words
Swedish	/ks/
Uzbek	Template:IPAslink
Venetian	Template:IPAslink	Usually
	Template:IPAslink	In Venexia, "Venice"
Vietnamese	Template:IPAslink

English

In English orthography, ⟨x⟩ is typically pronounced as the voiceless consonant cluster /ks/ when it follows the stressed vowel (e.g. ox), and the voiced consonant /ɡz/ when it precedes the stressed vowel (e.g. exam). It is also pronounced /ɡz/ when it precedes a silent ⟨h⟩ and a stressed vowel (e.g. exhaust). Due to yod-coalescence, the sequence ⟨xi⟩ before a vowel can be pronounced /kʃ/ resulting from earlier /ksj/, e.g. in -xion(-), -xious(-). Similarly, the sequence ⟨xu⟩ can be pronounced with /kʃ/ (e.g. flexure, sexual) or /ɡʒ/ (in luxury and its derivatives). Due to NG-coalescence, the sequence ⟨nx⟩ can be pronounced /ŋz/ in anxiety.

When ⟨x⟩ ends a word, it is always /ks/ (e.g. fax), except in loan words such as faux. When ⟨x⟩ does start a word, it is usually pronounced 'z' (e.g. xylophone, xanthan). When starting in some names or as its own representation, it is pronounced 'eks', in rare recent loanwords or foreign proper names, it can also be pronounced /s/ (e.g. the obsolete Vietnamese monetary unit xu) or /ʃ/ (e.g. Chinese names starting with Xi, like Xiaomi or Xinjiang). Many of the words that start with ⟨x⟩ are of Greek origin, standardized trademarks (Xerox), or acronyms (XC).

In abbreviations, it can represent "trans-" (e.g. XMIT for transmit, XFER for transfer), "cross-" (e.g. X-ing for crossing, XREF for cross-reference), "Christ-" (e.g. Xmas for Christmas, Xian for Christian), the "crys-" in crystal (XTAL), "by" (SXSW for South by Southwest), or various words starting with "ex-" (e.g. XL for extra large, XOR for exclusive-or, or the extinction symbol).

X is the third least frequently used letter in English (after ⟨q⟩ and ⟨z⟩), with a frequency of about 0.15% in words. There are very few English words that start with ⟨x⟩ (the fewest of any letter).

Romance languages

In Latin, ⟨x⟩ stood for /ks/. In the Romance languages, as a result of assorted phonetic changes, ⟨x⟩ has other pronunciations:

• In Catalan, ⟨x⟩ has four to three (depending on the dialect) main pronunciations; the most common is Template:IPAslink and/or Template:IPAslink; as in xarop ('syrup'). Others are: /(j)ʃ/ with the digraph ⟨ix⟩: mateix ('same'), /ks/; fixar ('to fix'), /ɡz/; examen. In addition, /(j)ʃ/ (from the digraph ⟨ix⟩) gets voiced to [(j)ʒ] before voiced consonants or vowels; caixmir ('kashmir') and peix espasa ('sword fish'). Catalan also has the digraph ⟨tx⟩, pronounced Template:IPAslink.
• In Galician and Leonese, ⟨x⟩ is pronounced Template:IPAslink in most cases (often used in place of etymological g or j). The pronunciation /ks/ occurs in learned words, such as taxativo (taxing). However, Galician speakers tend to pronounce it Template:IPAslink, especially when it appears before plosives, such as in externo ('external').
• In French, ⟨x⟩ usually represents /ks/ or (primarily in words beginning with ex- followed by a vowel) /ɡz/. It is pronounced Template:IPAslink in some city names such as Bruxelles (although some people pronounce it 'ks') or Auxerre; it is nevertheless pronounced /ks/ in Aix, the name of several towns. At the ends of other words, it is silent (or Template:IPAslink in liaison if the next word starts with a vowel). Two exceptions are pronounced Template:IPAslink: six ('six') and dix ('ten'). It is pronounced Template:IPAslink in sixième and dixième.
• In Italian, ⟨x⟩ is either pronounced /ks/, as in extra, uxorio, xilofono, or /ɡz/, as in exogamia, when it is preceded by ⟨e⟩ and followed by a vowel. In several related languages, notably Venetian, it represents the voiced sibilant Template:IPAslink. It is also used, mainly amongst young people, as a short written form for per (meaning "for"); for example, x sempre (Template:Gloss). This is because in Italian, the multiplication sign is called per. However, ⟨x⟩ is found only in loanwords, as it is not part of the standard Italian alphabet; in most words with ⟨x⟩, this letter may be replaced with ⟨s⟩ or ⟨ss⟩ (with different pronunciation: xilofono/silofono, taxi/tassì) or, rarely, by 'cs' (with the same pronunciation: claxon/clacson).
• In Portuguese, ⟨x⟩ has four main pronunciations; the most common is Template:IPAslink, as in xícara ('cup'). The other sounds are: /ks/ as in flexão ('flexion'); Template:IPAslink, when preceded by E and followed by a consonant, as in contexto (Template:IPAslink in European Portuguese), and in a small number of other words, such as próximo (close/next); and (the rarest) Template:IPAslink, which occurs in the prefix ⟨ex-⟩ before a vowel, as in exagerado ('exaggerated'). A rare fifth sound is /ɡz/, coexisting with Template:IPAslink and /ks/ as acceptable pronunciations in exantema and in words with the Greek prefix 'hexa-'.
• In Sardinian and Ligurian, ⟨x⟩ represents Template:IPAslink.
• In Old Spanish, ⟨x⟩ was pronounced Template:IPAslink, as it is still currently in other Iberian Romance languages. Later, the sound evolved to a Template:IPAslink sound. In modern Spanish, due to a spelling reform, whenever ⟨x⟩ is used for the Template:IPAslink sound it has been replaced with ⟨j⟩, including in words that originally had ⟨x⟩ such as ejemplo or ejercicio, though ⟨x⟩ is still retained for some names (notably México, even though Méjico may sometimes be used in Spain). Presently, ⟨x⟩ represents the sound Template:IPAslink (word-initially), or the consonant cluster /ks/ (e.g. oxígeno, examen). Rarely, it can be pronounced Template:IPAslink as in Old Spanish in some proper nouns such as Raxel (a variant of Rachel) and Uxmal.
• In Venetian, ⟨x⟩ represents the voiced alveolar sibilant Template:IPAslink, much like in Portuguese exagerado, English 'xylophone' or in the French sixième. Examples from medieval texts include raxon ('reason'), prexon ('prison'), dexerto ('desert'), and chaxa or caxa ('home'). Nowadays, the best-known word is xe ('is/are'). The most notable exception to this rule is the name Venexia, /veˈnɛsja/, in which ⟨x⟩ has evolved from the initial voiced sibilant Template:IPAslink to the present-day voiceless sibilant Template:IPAslink.

Other languages

In languages which adopted the Latin alphabet later, ⟨x⟩ is used for various sounds, in some cases inspired by Latin or its descendants, but in others for unrelated consonants. Since the various Romance pronunciations of ⟨x⟩ can often be written in other ways, the letter becomes available for other sounds.

• In Albanian, ⟨x⟩ represents Template:IPAslink while the digraph ⟨xh⟩ represents Template:IPAslink.
• It represents Template:IPAslink (voiceless velar fricative) in Apache, Azerbaijani, Kurdish (Hawar alphabet), Georgian (when Latinized), Lojban, Pashto (when Latinized), Tatar (Jaꞑalif, Zamanälif, official romanization of 2012), Uzbek, and Uyghur (Latin script).
• In Basque, ⟨x⟩ represents Template:IPAslink. Additionally, the digraph ⟨tx⟩ represents Template:IPAslink.
• In Hanyu Pinyin, Standard Chinese's official transcription system in China, Malaysia, Singapore, and Taiwan, the letter ⟨x⟩ represents the voiceless alveolo-palatal fricative Template:IPAslink, for instance in 'Xi', /ɕi/.
• In Dutch, ⟨x⟩ usually represents /ks/, except in the name of the island of Texel, which is pronounced Tessel. This is because of historical sound-changes in Dutch, where all /ks/ sounds have been replaced by Template:IPAslink sounds. Words with an ⟨x⟩ in the Dutch language are nowadays usually loanwords. In the Dutch-speaking part of Belgium, family names with ⟨x⟩ are not uncommon (e.g., Dierckxa and Hendrickx).
• In Esperanto, the x-convention replaces ⟨ĉ⟩, ⟨ĝ⟩, ⟨ĥ⟩, ⟨ĵ⟩, ⟨ŝ⟩, and ⟨ŭ⟩ with x-suffixes: ⟨cx⟩, ⟨gx⟩, ⟨hx⟩, ⟨jx⟩, ⟨sx⟩, and ⟨ux⟩.
• In German, generally pronounced /ks/; in native words, however, such as Ochs or wachsen, the cluster /ks/ is often written ⟨chs⟩.
• In transliterations of Indian languages, primarily Indo-Aryan languages, ⟨x⟩ represents the consonant cluster [kʃ] in alternate spellings of words containing Template:Script/Devanagari (kṣ), especially names such as Laxmi and Dixit. Less frequently, ⟨x⟩ is used to represent Template:Script/Devanagari Template:IPAslink.
• In Lao, based on romanization of Lao consonants, ⟨x⟩ represents Template:IPAslink, while appears to be homophonous with ⟨s⟩, it is a "low consonant" and affects the tone of the following vowel, e.g. in Lan Xang.
• In Maltese, ⟨x⟩ is pronounced Template:IPAslink or, in some cases, Template:IPAslink (only in loanwords such as 'televixin', and not for all speakers).
• In Nahuatl, ⟨x⟩ represents Template:IPAslink.
• In Nguni languages, ⟨x⟩ represents the alveolar lateral click Template:IPAslink.
• In Norwegian, ⟨x⟩ is generally pronounced /ks/, but since the 19th century, there has been a tendency to spell it out as ⟨ks⟩; it may still be retained in personal names, though it is fairly rare, and occurs mostly in foreign words and SMS language. Usage in Danish and Finnish is similar (while Swedish, on the other hand, makes frequent use of ⟨x⟩ in native words as well as in loanwords).
• In Pirahã, ⟨x⟩ symbolizes the glottal stop Template:IPAslink.
• In Polish, ⟨x⟩ was used prior to 19th century both in loanwords and native words and was pronounced /ks/ or /ɡz/, e.g., xiążę, xięstwo (now książę, księstwo). This was later replaced by ⟨ks⟩ and ⟨gz⟩ in almost all words and remained only in a few loanwords as 'xenia' (xenien), surnames as Axentowicz, Rexemowski, and Xiężopolski, names as Xawery, and Xymena, and abbreviations.
• In Vietnamese, ⟨x⟩ represents Template:IPAslink. This sound was [ɕ] in Middle Vietnamese, resembling the Portuguese Template:IPAslink, spelled ⟨x⟩.

An illustrative example of ⟨x⟩ as a "leftover" letter is the differing usage in three different Cushitic languages:

• Afar: voiced retroflex plosive Template:IPAslink
• Oromo: alveolar ejective Template:IPAslink
• Somali: voiceless pharyngeal fricative Template:IPAslink

Other systems

In the International Phonetic Alphabet, ⟨x⟩ represents a voiceless velar fricative.

Other uses

Main article: X (disambiguation)

• X mark has a widely accepted meaning of "negative" or "wrong".
• The Roman numeral X represents the number 10.
• In mathematics, x is commonly used as the name for an independent variable or unknown value. The modern tradition of using x, y, and z to represent an unknown (incognita) was introduced by René Descartes in La Géométrie (1637). As a result of its use in algebra, X is often used to represent unknowns in other circumstances (e.g. X-rays, The X-Files, and The Man from Planet X).
• On some identification documents, the letter X represents a non-binary gender, where F means female and M means male.
• In the Cartesian coordinate system, x is used to refer to the horizontal axis.
• It is also sometimes used as a typographic approximation for the multiplication sign, ×. In mathematical typesetting, x meaning an algebraic variable is normally in italic type ($x\!$), partly to avoid confusion with the multiplication symbol. In fonts containing both x (the letter) and × (the multiplication sign), the two glyphs are dissimilar.
• It can be used as an abbreviation for 'between' in the context of historical dating; e.g. "1483 x 1485".
• Maps and other images sometimes use an X to label a specific location, leading to the expression "X marks the spot".
• In art or fashion, the use of X indicates a collaboration by two or more artists, e.g. Aaron Koblin x Takashi Kawashima. This application, which originated in Japan, now extends to other kinds of collaboration outside the art world. This usage mimics the use of a similar mark in denoting botanical hybrids, for which scientifically the multiplication × is used, but informally, a lowercase "x" is also used.
• At the end of a letter or other correspondence, 'x' can mean a kiss; the earliest example of this usage cited by the Oxford English Dictionary is from 1878.
• An X rating denotes media, such as movies, that are intended for adults only.
• In the Korean language, a series of Xs is used as a visual bleep censor for subtitles and captions, serving the same role as an asterisk (*).
• In the C programming language, "x" preceded by zero (as in 0x or 0X) is used to denote hexadecimal literal values.
• X is commonly used as a prefix term in nouns related to the X Window System and Unix.

Related characters

Descendants and related characters in the Latin alphabet

• X with diacritics: Ẍ ẍ Ẋ ẋ X̂ x̂ ᶍ
• IPA-specific symbols related to X: χ
• Teuthonista phonetic transcription-specific symbols related to X:
  • U+AB56 ꭖ LATIN SMALL LETTER X WITH LOW RIGHT RING
  • U+AB57 ꭗ LATIN SMALL LETTER X WITH LONG LEFT LEG
  • U+AB58 ꭘ LATIN SMALL LETTER X WITH LONG LEFT LEG AND LOW RIGHT RING
  • U+AB59 ꭙ LATIN SMALL LETTER X WITH LONG LEFT LEG WITH SERIF
• ˣ : Modifier letter small x is used for phonetic transcription
• ₓ : Subscript small x is used in Indo-European studies

Ancestors and siblings in other alphabets

• Χ χ : Greek letter Chi, from which the following derive:
  • Ꭓ ꭓ : Latin chi
  • Х х : Cyrillic letter Kha
  • Ⲭ ⲭ : Coptic letter Khe, which derives from Greek Chi
  • 𐍇 : Gothic letter enguz, which derives from Greek Chi
  • 𐌗 : Old Italic X, which derives from Greek Chi, and is the ancestor of modern Latin X
    • ᚷ : Runic letter Gyfu, which may derive from old Italic X
• Ξ ξ : Greek letter Xi, which was used in place of Chi in the Eastern (and the modern) Greek alphabets

Other representations

Computing

• U+0058 X
• U+0078 x
• U+FF38 Ｘ
• U+FF58 ｘ

See also

• Template:Anl

External links

• Template:Commons-inline
• The dictionary definition of X at Wiktionary
• The dictionary definition of x at Wiktionary
• Template:Cite AmCyc