X (disambiguation)

From Wikipedia, the free encyclopedia

X is the twenty-fourth letter of the Roman alphabet. It can also refer to the following.

Contents 1 Science and technology 2 Mathematics 3 Computing 4 Industry and commerce 5 Music 6 Television, film and theatre 7 Video and computer games 8 Comics 9 Sport 10 Other uses 11 See also

[edit] Science and technology

• X-rays are form of electromagnetic radiation with a wavelength in the range of 10 to 0.1 nanometers.
• In electrical engineering, X is the symbol for reactance.
• In radio, the X band ranges from 8 to 12.5 GHz.
• X is the center of a square face of the Brillouin zone of a face-centered cubic lattice.
• Haplogroup X (mtDNA) is a human mitochondrial DNA (mtDNA) haplogroup.
• In genetics, X denotes the X chromosome; in sex, XX denotes female in the XY sex-determination system.
• Negative X is a chemical mixture that ignites in the presence of water.
• In chemistry, X is used to represent a halogen atom or ion. This is generally used to represent any halogen in a general formula demonstrating reactions or compounds common to all halogens and is used instead of the symbol for the element.
• In aeronautics, X is the designation given to an experimental aircraft of the US government, such as the X-1 rocketplane that first broke the sound barrier. It is also a prefix to experimental types of US military aircraft, such as the XB-70.
• Planet X is a hypothetical planet in the Solar System beyond the orbit of Neptune.
• X stands for a comet of unknown orbit, as in X/1106 C1, one of whose fragments is thought to have been the Great Comet of 1882.
• X stands for a December 1 through 15 discovery, in the provisional designation of a comet (e.g. C/1927 X1, Comet Skjellerup-Maristany) or asteroid (e.g. (3757) 1982 XB).
• In military science, X is the US Navy hull classification symbol for Submersible Craft.
• In photography, X denotes exact time in flash synchronization.
• In optics, an x marks the magnification of a lens or instrument. A 2x lens shows an image twice bigger than reality.

[edit] Mathematics

• x commonly represents an unknown variable. Even though any letter can be used, x is the most common choice. This usage can be traced back to the Arabic word šay' شيء = "thing", which in translated algebra texts and similar was taken into Old Spanish with the pronunciation "šei", which was written xei, which was soon habitually abbreviated to x. (Spanish pronunciation of "x" has changed since.) But some sources say that this x is an abbreviation of Latin causa which was a translation of Arabic شيء. That started the habit of using letters to represent quantities in algebra. In mathematics a "curly x" () is often used to avoid potential confusion with the multiplication symbol. By extension, "X" has come to represent a generic placeholder variable, whose value is unknown or secret but within a set defined by context, as in project X or mister X.
• x is the usual symbol for the variable represented on the horizontal axis (ordinate) in analytic geometry.
• In Roman numerals, X denotes ten (there are also separate Unicode characters for this number, 0x2169 "Ⅹ" and 0x2179 "ⅹ").
• The symbol (×), similar to the lowercase x, denotes the multiplication of two numbers, the cross product of two vectors, or the Cartesian product of two sets.

[edit] Computing

• X Window System is a windowing system for bitmap displays.
• Mac OS X is a computer operating system developed and sold by Apple Computer, Inc.
• Ctrl-X (in Windows) and Command-X (in MacOS), the keyboard shortcut for cutting, that is, removing the selected text, image or sound and placing it on the clipboard.
• X designates an ITU-T series of recommendations on Data networks and open system communication, including, for example, X.509.
• x is the repetition operator in the Perl programming language.
• x denotes the multiplication of the CD-ROM (and DVD) disc spin and transfer rate compared to the original speed. It is also used to measure the speed of other storage devices such as flash cards.
• .x is the file extension for a DirectX 3D polygon mesh.

[edit] Industry and commerce

• In economics, especially national income accounting, X is usually used to represent exports.
• The X (automobile) is a French car produced in 1908 and 1909.
• In finance, X is the U.S. ticker symbol for United States Steel Corporation.

[edit] Music

• See X (band) for bands named "X".
• See X (album) for albums entitled "X".
• X is a song from the 2001 album Toxicity by System of a Down.
• X is a song by rapper Xzibit off his album Restless.
• X is a song by the pop group Liberty X.

[edit] Television, film and theatre

• X is a rating given to films suitable for an adult-only audience; see X-rated. NC-17 has replaced the X rating in the United States. The United Kingdom replaced the X rating with the 18 certificate. Australia retains the X rating.
• The X-Files is an American science fiction TV series.
• In both JFK and The X-Files, X is a mysterious informant who supplies the main character with information regarding a government conspiracy.
• Malcolm X (film) is a film by Spike Lee.
• X is the title of a 1928 German film; see X (film).
• X is also the title of a 1963 American science-fiction film; see X (1963 film).
• The X is a Canadian children's television program produced by the Canadian Broadcasting Corporation.
• The X's is an American animated television series.
• X the Eliminator is a character in the animated television series Harvey Birdman, Attorney at Law, shown on Adult Swim.
• Theatre X is an American theatre company based in Milwaukee, Wisconsin
• Kamen Rider X is a Japanese TV series.

[edit] Video and computer games

• Mega Man X is the main character of the Mega Man X video game series.
• X is a game for Nintendo's original Game Boy.
• X: Beyond the Frontier is a space simulation computer game.
• Radio X is a fictional radio station in the 2004 video game Grand Theft Auto:San Andreas.
• X is the name of an event showcasing Microsoft's Xbox console.

[edit] Comics

• See X (comics) for a list of comics entitled "X".
• In superhero comic books, an X usually denotes a connection to the popular X-Men franchise, especially when used as a prefix.
• X (aka X/1999) is a Japanese manga which was later made into a movie and anime series.
• The X-gun is a weapon featured in the manga and anime series Gantz.

[edit] Sport

• X Division is a style of professional wrestling.
• X is a pseudonym used by Carl Ouellet as a masked professional wrestler.
• In Gridiron football playbooks, X often represents the players on the defense, and O the offense, producing the expression "X's and O's" to describe the plays as drawn up on paper, in contrast to the execution thereof.

[edit] Other uses

• In legal documents, X can stand for the signature of an illiterate signatory, as long as the document is countersigned by a literate witness. In the Middle Ages, this represented a cross and so signified a Christian signatory, whereas illiterate Jews used a circle (kikel).
• In games such as tic tac toe (naughts and crosses), X is a representation of a cross.
• On paper ballots with square boxes, the symbol used in America to indicate one's choice is often in the form of an X and is so called. This extends to similar boxes on other forms. However, in Japan and Korea, boxes have a circle drawn in them to indicate one's choice, while those which are rejected are marked with an X. In Europe and many Commonwealth countries, rejection is also signified with an X, while a tick indicates one's selection.
• In written communication, X represents a kiss. It can be paired with the letter O to convey a warm sentiment (traditionally Hugs and Kisses) and is typically used as a closing, e.g. "XO, Bob".
• In cabalistic philosophy, X references both birth and death.
• In clothing, X is used as an abbreviation for extra, such as XXL for extra-extra-large or XS for extra-small.
• X is an abbreviation for Christ, as in Xmas (Christmas), X(t)ian (Christian), and Xianity (Christianity), due to its Greek name.
• In beverages, X is a symbol for an alcoholic proof of 50; multiple X's indicate multiples of 50.
• In ten-pin bowling, X is the symbol for a strike — knocking down all ten pins in a the first roll of a frame.
• In Italian, X is used as an abbreviation for per (for) and for other uses of per, ie. xché for perché (because).
• X appears in various jargon or trade abbreviations, such as "xtal" (Crystal), "xant" (chrysanthemum), "reXn" or "rxn" (reaction), "Xlation" (translation), "SXSW" (South by Southwest festival), "RX" (receive) or (recrystallized), "TX" (transmit), "DX" (distance), and "WX" (weather).
• In semiotics, a superimposed X denotes elimination, prohibition or erasure.
• In sociology, X denotes Generation X.
• The drug ecstasy is sometimes known by the slang term "X"
• As the first letter of a postal code, in Canada X stands for Nunavut and the Northwest Territories.
• In publishing, X is used in ISBN and ISSN numbers as an eleventh one-digit numeral, following 9.
• In philately, X-cancel is a term denoting a cancellation in pen or pencil in the form of an "X"
• Malcolm X changed his surname to "X" to symbolize that his African name was lost in slavery; some other members of the Nation of Islam followed his example.
• In French education, X is a nickname for the École Polytechnique and its alumni.
• X is a roller coaster at Six Flags Magic Mountain.
• In treasure-hunting, X is used to designate the location of treasure, as in "X marks the spot".
• In United States politics, X is the pseudonym of the person who blew the whistle on the Watergate crisis.
• In United States public policy, X is the author (George F. Kennan) of the X article published in Foreign Affairs.

[edit] See also

• Ex
• The X, for multiple meanings of this phrase.
• Saint Andrew's Cross, which bears the shape of an "X".
• XX
• XXX
• XXXX (disambiguation)