X

For technical reasons, ":X" redirects here. For the keyboard symbol, see List of emoticons.

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

X or 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/), plural exes.^[2]

X
X x
Usage
Writing system	Latin script
Type	Alphabetic and logographic
Language of origin	Latin language Greek language
Sound values	[x] [χ] [ħ] [kʰ] [ks] [ʃ] [ɕ] [tʼ] [ʒ] [ɖ] [ʔ] [ǁ] [ɡʒ][1] [kʃ] [d͡z] [d͡ʒ] [t͡s] [t͡ʃ] [sʲ] [z] [ɡz] [∅] /ɛks/
In Unicode	U+0058, U+0078
Alphabetical position	24
History
Development	𓊽 𐤎 𐤎 𐊑 𐊐 𐊐 X x
Time period	~−700 to present
Descendants	× ⨘ ⨉ ⨯ ✗ ☒ ꭓ X̧
Sisters	Х 𐍇 Ⴕ ქ Ⴟ ჯ
Other
Associated graphs	x(x)
Writing direction	Left-to-right
This article contains phonetic transcriptions in the International Phonetic Alphabet (IPA). For an introductory guide on IPA symbols, see Help:IPA. For the distinction between [ ], / / and ⟨ ⟩, see IPA § Brackets and transcription delimiters.

History

Western Greek Chi	Etruscan X	Latin X

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/, /ks/
Afar	/ɖ/
Albanian	/dz/
Azeri	/x/
Basque	/ʃ/
Catalan	/ʃ/	Usually (word-initially, after consonants, i, au, or eu, in some surnames such as Rexach)
	/gz/
	/ks/
Standard Chinese (Pinyin)	/ɕ/
Cou	/ɨ/ ~ /ʉ/
Dutch	/ks/	Usually, mainly used in loanwords
	/s/	In Texel
English	/ks/	Usually; before an unstressed vowel
	/gz/	Before a stressed vowel
	/z/	Word-initially
	/h/	Don Quixote, Oaxaca, and words derived from 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
	/z/	Word-finally with liaison; in sixième (6th) and dixième (10th)
	/s/	In six (6), dix (10), Auxerre, and Bruxelles (Brussels)
Galician	/ʃ/	Usually
	/(k)s/	Some learned loanwords
German	/ks/	Mainly used in loanwords
Indonesian	/s/	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 always replaced by the letters 'ks'. For example, the word 'maximum' and 'climax' in Indonesian would be 'maksimal' and 'klimaks'. Letter x on the middle or the end of a word only occurs in names. Mainly used in loanwords for science.
Italian	/ks/	Mainly used in learned loanwords
Kurdish	/x/
Lao romanization	/s/	A "low consonant", affects the tone of the following vowel
Leonese	/ʃ/
Ligurian	/ʒ/
Maltese	/ʃ/
Mayan (ALMG)	/ʃ/
Nahuatl	/ʃ/
Nguni	/ǁ/
Norwegian	/ks/	Archaic
Occitan	/t͡s/	Usually
	/s/	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	/tʼ/
Pirahã	/ʔ/
Polish	/ks ~ gz/
Portuguese	/ʃ/	Usually, always when word-initially
	/ks/	Found between vowels in some words, mainly in those that entered the language recently
	/s/	When preceded by ⟨e⟩ and succeeded by a consonant
	/z/	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 /z/
Sardinian	/ʒ/
Sicilian	/ʃ/	Old Sicilian words and names, e.g. Craxi and Giancaxio
	/k(ə)s(ə)/	Loanwords
Somali	/ħ/
Spanish	/(k)s/	Usually
	/s/	Word-initially
	/ʃ/, /t͡ʃ/, /x/	In some names and words
Swedish	/ks/
Uzbek	/χ/
Venetian	/z/	Usually
	/s/	In Venexia, "Venice"
Vietnamese	/s/

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).^[3] 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.^[4] 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 three pronunciations; the most common is /ʃ/; as in xarop ('syrup'). Others are: /ks/; fixar ('to fix'), /ɡz/; examen. In addition, /ʃ/ gets voiced to [ʒ] before voiced consonants; caixmir. Catalan also has the digraph ⟨tx⟩, pronounced /tʃ/.
• In Galician and Leonese, ⟨x⟩ is pronounced /ʃ/ 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 /s/, 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 /s/ 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 /z/ in liaison if the next word starts with a vowel). Two exceptions are pronounced /s/: six ('six') and dix ('ten'). It is pronounced /z/ in sixième and dixième.
• In Italian, ⟨x⟩ is either pronounced /ks/, as in extra, uxorio, xilofono,^[5] 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 /z/. It is also used, mainly amongst young people, as a short written form for "per" (meaning "for"); for example, "x sempre" ("forever"). 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 /ʃ/, as in xícara ('cup'). The other sounds are: /ks/ as in flexão ('flexion'); /s/, when preceded by E and followed by a consonant, as in contexto (/ʃ/ in European Portuguese), and in a small number of other words, such as próximo (close/next); and (the rarest) /z/, which occurs in the prefix "ex-" before a vowel, as in exagerado ('exaggerated'). A rare fifth sound is /ɡz/, coexisting with /z/ and /ks/ as acceptable pronunciations in exantema and in words with the Greek prefix 'hexa-'.
• In Sardinian and Ligurian, ⟨x⟩ represents /ʒ/.
• In Old Spanish, ⟨x⟩ was pronounced /ʃ/, as it is still currently in other Iberian Romance languages. Later, the sound evolved to a /x/ sound. In modern Spanish, due to a spelling reform, whenever ⟨x⟩ is used for the /x/ 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 /s/ (word-initially), or the consonant cluster /ks/ (e.g. oxígeno, examen). Rarely, it can be pronounced /ʃ/ 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 /z/, 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 /z/ to the present-day voiceless sibilant /s/.

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 /dz/ while the digraph ⟨xh⟩ represents /dʒ/.
• It represents /x/ (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 /ʃ/. Additionally, the digraph ⟨tx⟩ represents /tʃ/.
• In Hanyu Pinyin, Standard Chinese's official transcription system in China, Malaysia, Singapore, and Taiwan, the letter ⟨x⟩ represents the voiceless alveolo-palatal fricative /ɕ/, 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 /s/ 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 'क्ष' (kṣ), especially names such as Laxmi and Dixit. Less frequently, ⟨x⟩ is used to represent 'ख़' /x/.
• In Lao, based on romanization of Lao consonants, ⟨x⟩ represents /s/, 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 /ʃ/ or, in some cases, /ʒ/ (only in loanwords such as 'televixin', and not for all speakers).
• In Nahuatl, ⟨x⟩ represents /ʃ/.
• In Nguni languages, ⟨x⟩ represents the alveolar lateral click /ǁ/.
• 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 /ʔ/.
• 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 /s/. This sound was [ɕ] in Middle Vietnamese, resembling the Portuguese /ʃ/, spelled ⟨x⟩.

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

• Afar: voiced alveolar implosive /ɗ/
• Oromo: alveolar ejective /tʼ/
• Somali: voiceless pharyngeal fricative /ħ/

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.^[6][7]
• 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).^[8] As a result of its use in algebra, X is often used to represent unknowns in other circumstances (e.g. X-rays, Generation X, 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.^[9][10]
• 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 (${\displaystyle x\!}$), 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".^[11]
• 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.^[12] 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;^[13] the earliest example of this usage cited by the Oxford English Dictionary is from 1878.^[14]
• 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 (*).^[15][16]
• 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.^[2]

Related characters

Descendants and related characters in the Latin alphabet

• X with diacritics: Ẍ ẍ Ẋ ẋ X̂ x̂ ᶍ^[17]
• IPA-specific symbols related to X: χ
• Teuthonista phonetic transcription-specific symbols related to X:^[18]
  • 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^[19]

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

Character information

Preview	X		x		Ｘ		ｘ
Unicode name	LATIN CAPITAL LETTER X		LATIN SMALL LETTER X		FULLWIDTH LATIN CAPITAL LETTER X		FULLWIDTH LATIN SMALL LETTER X
Encodings	decimal	hex	dec	hex	dec	hex	dec	hex
Unicode	88	U+0058	120	U+0078	65336	U+FF38	65368	U+FF58
UTF-8	88	58	120	78	239 188 184	EF BC B8	239 189 152	EF BD 98
Numeric character reference	X	X	x	x	Ｘ	Ｘ	ｘ	ｘ
EBCDIC family	231	E7	167	A7
ASCII[a]	88	58	120	78

Other

NATO phonetic	Morse code
Xray	▄▄▄ ▄ ▄ ▄▄▄ ⓘ

Signal flag	Flag semaphore	American manual alphabet (ASL fingerspelling)	British manual alphabet (BSL fingerspelling)	Braille dots-1346 Unified English Braille

See also

• X mark

Notes

1. Also for encodings based on ASCII, including the DOS, Windows, ISO-8859 and Macintosh families of encodings.

References

1. as in the English word luxurious
2. "X", Oxford English Dictionary, 2nd edition (1989); Merriam-Webster's Third New International Dictionary of the English Language, Unabridged (1993); "ex", op. cit.
3. Venezky, Richard (1 January 1970). The Structure of English Orthography. The Hague: Walter de Gruyter. p. 40. ISBN 978-3-11-080447-8. Archived from the original on 27 April 2017. Retrieved 29 October 2016.
4. Mička, Pavel. "Letter frequency (English)". Algoritmy.net. Archived from the original on 4 March 2021. Retrieved 9 February 2014.
5. "Dizionario di ortografia e pronunzia" [Dictionary of Spelling and Pronunciation]. Dizionario di ortografia e pronunzia (in Italian). Archived from the original on 16 April 2018. Retrieved 9 February 2014.
6. Gordon, Arthur E. (1983). Illustrated Introduction to Latin Epigraphy. University of California Press. p. 44. ISBN 9780520038981. Retrieved 3 October 2015. roman numerals.
7. King, David A. (2001). The Ciphers of the Monks. Franz Steiner Verlag. p. 282. ISBN 9783515076401. Archived from the original on 4 January 2021. Retrieved 22 November 2020. In the course of time, I, V and X became identical with three letters of the alphabet; originally, however, they bore no relation to these letters.
8. Cajori, Florian (1928). A History of Mathematical Notations. Chicago: Open Court Publishing. p. 381. ISBN 9780486161167. Archived from the original on 13 April 2021. Retrieved 22 November 2020. See History of algebra.
9. Holme, Ingrid (2008). "Hearing People's Own Stories". Science as Culture. 17 (3): 341–344. doi:10.1080/09505430802280784. S2CID 143528047.
10. "New Zealand Passports - Information about Changing Sex / Gender Identity". Archived from the original on 23 September 2014. Retrieved 6 October 2014.
11. "X marks the spot". Archived from the original on 4 June 2016. Retrieved 21 June 2016.
12. "X: Mark of Collaboration - Issue No. 0053X - Arkitip, Inc". arkitip.com. Archived from the original on 17 May 2016. Retrieved 22 March 2016.
13. Epstein, Nadine (7 October 2020). "A whole lot of history behind 'x' and 'o', kiss and hug". The Washington Post. Archived from the original on 1 April 2018. Retrieved 12 March 2021.
14. "X, n." OED Online (Oxford: Oxford University Press, September 2022), §6. Accessed 11 November 2022.
15. "'찐따', 'X랄하다'...욕도 전통을 가진다?" ['loser', 'fXing'... swear words also have a tradition?]. www.goeonair.com (in Korean). Archived from the original on 18 January 2024. Retrieved 22 August 2023.
16. 참바다 (15 January 2021). 시사칼럼 우리 시대의 상징과 은유 (in Korean). e퍼플. ISBN 979-11-6569-712-9.
17. Constable, Peter (19 April 2004). "L2/04-132 Proposal to add additional phonetic characters to the UCS" (PDF). Archived (PDF) from the original on 11 October 2017. Retrieved 24 March 2018.
18. Everson, Michael; Dicklberger, Alois; Pentzlin, Karl; Wandl-Vogt, Eveline (2 June 2011). "L2/11-202: Revised proposal to encode "Teuthonista" phonetic characters in the UCS" (PDF). Archived (PDF) from the original on 11 October 2017. Retrieved 24 March 2018.
19. Anderson, Deborah; Everson, Michael (7 June 2004). "L2/04-191: Proposal to encode six Indo-Europeanist phonetic characters in the UCS" (PDF). Archived (PDF) from the original on 11 October 2017. Retrieved 24 March 2018.

External links

• Media related to X at Wikimedia Commons
• The dictionary definition of X at Wiktionary
• The dictionary definition of x at Wiktionary
• "X" . The American Cyclopædia. 1879.