X, or x, is the twenty-fourth and third-to-last letter in 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 ), plural exes. X is regularly pronounced as "ks". History In Ancient Greek, 'Χ' and 'Ψ' were among several variants of the same letter, used originally for and later, in western areas such as Arcadia, as a simplification of the digraph 'ΧΣ' for . In the end, more conservative eastern forms became the standard of Classical Greek, and thus 'Χ' (Chi) stood for (later ; palatalized to in Modern Greek before front vowels). However, the Etruscans had taken over 'Χ' from western Greek, and it therefore stands for in Etruscan and Latin. The letter 'Χ' ~ 'Ψ' for was a Greek addition to the alphabet, placed after the Semitic letters along with phi 'Φ' for . Pronunciation and use English In English orthography, is typically pronounced as the voiceless consonant cluster when it follows the stressed vowel (e.g. ox), and the voiced consonant when it precedes the stressed vowel (e.g. exam). It is also pronounced when it precedes a silent and a stressed vowel (e.g. exhaust). Before , or , it can be pronounced or (e.g. sexual and luxury); these result from earlier and . It also makes the sound in words ending in -xion (except for axion). When ends a word, it is always (e.g. fax), except in loan words such as faux (see French, below). There are very few English words that start with (the fewest of any letter). When does start a word, it is usually pronounced 'z' (e.g. xylophone, xenophobia, and 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 (e.g. the obsolete Vietnamese monetary unit xu) or (e.g. Chinese names starting with Xi like Xiaomi or Xinjiang). Many of the words that start with are of Greek origin, or 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), or various words starting with "ex-" (e.g. XL for extra large, XOR for exclusive-or, or the extinction symbol). X is the