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X: American band whose tales of urban decay, corruption, and sleaze, delivered with skilled musicianship and unique vocal harmonies, marked them as important contributors to the punk movement. The original members ...
X Club: private scientific dining club of Victorian London, remarkable for the power that its nine members exerted on the scientific and cultural climate of late-19th-century England.
X-ray: electromagnetic radiation of extremely short wavelength and high frequency, with wavelengths ranging from about 10⁻⁸ to 10⁻¹² metre and corresponding frequencies from about 10¹⁶ to 10²⁰ hertz (Hz).
X-ray diffraction: a phenomenon in which the atoms of a crystal, by virtue of their uniform spacing, cause an interference pattern of the waves present in an incident beam of X rays. ...
X-ray source: in astronomy, any of a class of cosmic objects that emit radiation at X-ray wavelength. Because the Earth's atmosphere absorbs X rays very efficiently, X-ray telescopes and detectors must be ...
X-ray style: manner of depicting animals by drawing or painting the skeletal frame and internal organs. It is one of the characteristic styles of the art of some prehistoric hunting cultures.
X-ray telescope: instrument designed to detect and resolve X rays from sources outside the Earth's atmosphere. Because of atmospheric absorption, X-ray telescopes must be carried to high altitudes by rockets or balloons ...
X-ray tube: evacuated electron tube that produces X rays by accelerating electrons to a high velocity with a high-voltage field and causing them to collide with a target, the anode plate. The ...
X-trisomy: sex chromosome disorder of human females, in which three X chromosomes are present, rather than the normal pair. More common than Turner's syndrome, where only one X chromosome is present, ...
Xai-Xai: port town, southern Mozambique. Located on the eastern bank of the Limpopo River near its mouth, the town is a market centre for cashew nuts, rice, corn (maize), cassava, and ...
Xaignabouri, Muang: town, northwestern Laos. Located about 18 miles (29 km) west of the Mekong River, at the base of high hills, Xaignabouri has a sawmill and trades in such forest products ...
Xankandi: city, southwestern Azerbaijan. Situated at the foot of the eastern slopes of the Karabakh Range, the city was founded after the October Revolution (1917) on the site of the village ...
xanthate: any of a class of organic salts formed by treatment of an alcohol with carbon disulfide in the presence of an alkali. The term is derived from the Greek word ...
Xanthi: city and nomos (department) in the Thrace (Thraki) region of eastern Greece. The city, which is situated below the Rhodope massif at the head of the narrow Eskeje (Esketze) Valley, ...
xanthinuria: rare inherited disorder of purine metabolism that results from a deficiency in the enzyme xanthine oxidase. Normally this enzyme breaks down the purine base xanthine to uric acid, which is ...
Xanthophyta: division or phylum of algae commonly known as yellow-green algae (q.v.).
Xanthus: principal city of ancient Lycia. It is situated on a cliff above the mouth of the Koca (Xanthus) River in what is now western Turkey. The early history of Xanthus ...
Xavier University: private, coeducational institution of higher learning in Cincinnati, Ohio, U.S. It is affiliated with the Jesuit order of the Roman Catholic church. The university comprises colleges of Arts and Sciences, ...
Xavier, Saint Francis: the greatest Roman Catholic missionary of modern times, who was instrumental in the establishment of Christianity in India, the Malay Archipelago, and Japan. In Paris in 1534 he pronounced vows ...
Xenacanthus: long-surviving but now extinct genus of freshwater sharks. Xenacanthus survived from the end of the Devonian Period, some 360 million years ago, to about the end of the Triassic Period, ...
Xenakis, Iannis: Romanian-born French composer, architect, and mathematician who originated musique stochastique, music composed with the aid of electronic computers and based upon mathematical probability systems.
xenarthran: an ancient lineage of mammals comprising the armadillos (order Cingulata) and the sloths and anteaters (order Pilosa). The namesake feature shared by all members of Xenarthra is seen in the ...
Xenia: city, seat (1804) of Greene County, southwestern Ohio, U.S., near the Little Miami River, 16 mi (26 km) east-southeast of Dayton. It was founded in 1803 by Joseph C. Vance, ...
Xenicidae: bird family of the order Passeriformes; its members are commonly known as New Zealand wrens. The three living species are the rock wren (Xenicus gilviventris) and the rare bush wren ...
Xenocrates: Greek philosopher, pupil of Plato, and successor of Speusippus as the head of the Greek Academy, which Plato founded about 387 BC. In the company of Aristotle he left Athens ...
xenolith: rock fragment within an intrusive igneous body that is unrelated to the igneous body itself. Xenoliths, which represent pieces of older rock incorporated into the magma while it was still ...
xenon: chemical element, heavy and extremely rare gas of Group 0 (noble gases) of the periodic table. It was the first noble gas found to form true chemical compounds. More than ...
Xenophanes: Greek poet and rhapsode, religious thinker, and reputed precursor of the Eleatic school of philosophy, which stressed unity rather than diversity and viewed the separate existences of material things as ...
Xenophon: Greek historian, author of the Anabasis. Its prose was highly regarded by literary critics in antiquity and had strong influence on Latin literature.
xenotime: widely distributed phosphate mineral, yttrium phosphate (YPO₄, though large proportions of erbium commonly replace yttrium), that occurs as brown, glassy crystals, crystal aggregates, or rosettes in igneous rocks and associated ...
xeroderma pigmentosum: rare, recessively inherited skin condition in which resistance to sunlight and other radiation beyond the violet end of the spectrum is lacking. On exposure to such radiation the skin erupts ...
xerophyte: any plant adapted to life in a dry or physiologically dry habitat (salt marsh, saline soil, or acid bog) by means of mechanisms to prevent water loss or to store ...
Xerox Corporation: major U.S. corporation and first manufacturer of xerographic, plain-paper copiers. Headquarters are in Stamford, Connecticut.
Xerox PARC: division established in 1970 by Xerox Corporation in Palo Alto, California, U.S., to explore new information technologies that were not necessarily related to the company's core photocopier business. Many innovations ...
Xerxes I: Persian king (486-465 BC), the son and successor of Darius I. He is best known for his massive invasion of Greece from across the Hellespont (480 BC), a campaign marked ...
Xhosa: a cluster of related peoples living primarily in Eastern Cape province, South Africa, and forming part of the southern Nguni group of Bantu-speaking peoples. The main Xhosa groups are the ...
Xhosa language: a Bantu language spoken by seven million people in South Africa, especially in Eastern province. Xhosa is a member of the Southeastern, or Nguni, subgroup of the Bantu group of ...
Xi'an monument: inscribed stone monument that records the early missionary activity of Nestorian Christians in China. It was discovered by Jesuit missionaries in 1625 in the province of Shaanxi, China. The monument, ...
Xia Gui: one of China's greatest masters of landscape painting, cofounder with Ma Yuan of the Ma-Xia school. The album leaf and the hand scroll with a continuous panorama were his predominant ...
Xia Yan: Chinese writer, journalist, and playwright known for his leftist plays and films.
Xiang language: Chinese language that is spoken in Hunan province. The two major varieties of Xiang are New Xiang and Old Xiang. New Xiang, which is spoken predominantly around Changsha, the capital ...
Xiangkhoang: town, north-central Laos. Xiangkhoang lies just south of the Plain of Jarres and is situated in the Xiangkhoang Plateau. Corn (maize) and rice are raised by valley Lao north of ...
Xiangkhoang Plateau: dissected upland of complex geologic structure in north-central Laos. The plateau constitutes a western extension of the northern Annamite Chain; it is drained principally by the Ngum and Ngiap (Nhiep) ...
Xiao Hong: Chinese fiction writer known for her novels and stories set in the northeast during the 1930s.
xiaozhuan: in Chinese calligraphy, a standardized and simplified form of the earlier dazhuan script, in which all lines are of even thickness and curves and circles are relatively ...
Xie He: Chinese figure painter and critic who is best remembered for collating or inventing the famous "Six Principles" (liufa) of Chinese painting.
Xie Jun: chess grandmaster who was twice women's world chess champion, from 1991 to 1996 and again from 1999 to 2001. See the table of women's world chess champions.
Xie Lingyun: prominent Chinese writer of the Six Dynasties era, known chiefly as a nature poet.
Xin Qiji: Chinese poet and master soldier whose ci (poems written to existing musical patterns) are considered by many critics to be the best of the Southern Song dynasty ...
xingshu: a semicursive Chinese script that developed out of the Han dynasty lishu script at the same time that the standard kaishu script was evolving ...
Xingu River: river in Mato Grosso and Para states, Brazil. The river rises on the Planalto (plateau) do Mato Grosso, in the drainage basin framed by the Serra do Roncador and the ...
Xiong Foxi: Chinese playwright who helped create popular drama intended to entertain and educate the peasantry.
Xiongnu: nomadic pastoral people who at the end of the 3rd century BC formed a great tribal league that was able to dominate much of Central Asia for more than 500 ...
Xipe Totec: (Nahuatl: "Our Lord the Flayed One"), pre-Columbian Mexican god of spring (the beginning of the rainy season) and of new vegetation; he was also the patron of goldsmiths.
Xirgu, Margarita: Catalan actress and producer whose greatest contribution was her advancement of the plays of Federico Garcia Lorca.
Xiuhtecuhtli: ("Old God"), Aztec god of fire, thought to be the creator of all life. "Old God" is a reflection of his relative age in the Aztec pantheon. In association with ...
Xiyouji: foremost Chinese comic novel, written by Wu Cheng'en, a novelist and poet of the Ming dynasty (1368-1644). The novel is based on the actual 7th-century pilgrimage of the Buddhist monk ...
Xochicalco: fortified ancient city known for its impressive ruins. It is located on the top of a large hill and parts of surrounding hills near Cuernavaca, in Morelos state, Mexico.
Xochimilco: district of Mexico City and delegacion (legation), central Distrito Federal (Federal District), central Mexico. It lies at 7,461 feet (2,274 metres) above sea level in the Valley ...
Xochiquetzal: (Nahuatl: "Precious Feather Flower"), Aztec goddess of beauty, sexual love, and household arts. She is also associated with flowers and plants and, in myth, came from Tamoanchan, the verdant paradise ...
Xu Beihong: influential Chinese artist and art educator who, in the first half of the 20th century, argued for the reformation of Chinese art through the incorporation of lessons from the West.
Xu Wei: colourful figure in the history of Chinese painting who is known for having been a child prodigy, bureaucrat, apparent madman, and painter.
Xu Yue: Chinese astronomer and mathematician.
Xu Zhimo: Chinese poet who strove to loosen Chinese poetry from its traditional forms and to reshape it under the influences of Western poetry and the vernacular Chinese language.
xuanji: Chinese jade form found in the Shang (c. 1600-1046 BC) and Zhou (1046-256 BC) dynasties. It is a flat disk similar in shape to the bi, except ...
Xuanzang: Buddhist monk and Chinese pilgrim to India who translated the sacred scriptures of Buddhism from Sanskrit into Chinese and founded in China the Buddhist Consciousness Only school. His fame rests ...
xylem: in botany, part of the vascular system that conveys water and dissolved minerals from the roots to the rest of the plant and may also furnish mechanical support. Xylem consists ...
xylene: any of three isomeric dimethylbenzenes [which have the same chemical formula, C₆H₄(CH₃)₂, but different molecular structure], used as solvents, as components of aviation fuel, and as raw materials for the ...
xylophone: (from Greek xylon and phone: "wood" and "sound"), percussion instrument consisting of a set of graduated, tuned wooden bars supported at nodal (nonvibrating) points and struck with padded mallets. The ...
XYY-trisomy: relatively common human sex chromosome anomaly in which a male has two Y chromosomes rather than one. It occurs in 1 in 500-1,000 live male births, and individuals with the ...
XYZ Affair: diplomatic incident that, when made public in 1798, nearly involved the United States and France in war. Pres. John Adams dispatched three ministers to France in 1797 to negotiate a ...