Encyclopædia Britannica Australia -

Encyclopedias since 1768

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X ... Xiongnu

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 were Exene Cervenka (original name Christine Cervenka; b. Feb. 1, ...
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. The atomic planes of the crystal act on the X ...
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 carried high above it by spacecraft to observe objects that ...
X-ray style: manner of depicting animals by drawing or painting the skeletal frame and internal organs, one of the characteristic styles of the art of prehistoric hunting cultures. The origin of the style can be traced to the Mesolithic art of northern ...
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 or placed in orbit outside the atmosphere. Balloon-borne telescopes are ...
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 tube consists of a source of electrons, the cathode, which ...
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, X-trisomy usually remains undetected because affected individuals appear normal, experience ...
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 sorghum raised in the surrounding area, which is irrigated by ...
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 as rattan, bamboo, stick lac, and benzoin; vast teak resources ...
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 of Khankendy and was renamed Stepanakert in 1923 for Stepan ...
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 xanthos, for "yellow," in reference to the compound potassium ethyl ...
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, is the seat of a metropolitan bishop of the Greek ...
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 then excreted. In the absence of the enzyme, xanthine 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 is unclear: although it is mentioned in early Lycian inscriptions, ...
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, Business Administration, and Social Sciences. In addition to undergraduate studies, ...
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 as one of the first seven members of the Society ...
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, 208 million years ago. Xenacanthus had a slim, elongated body ...
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 lower backbone. The lumbar vertebrae are "xenarthrous"; that is, they ...
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, who gave it a Greek name meaning "hospitality." The arrival ...
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 (X. longipes) on South Island and, common to both islands, ...
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 after Plato's death in 348/347, returning in 339 on his ...
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 fluid, may be located near their original positions of detachment ...
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 412 times heavier than air, xenon is colourless, odourless, and ...
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 apparent rather than real.
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 pegmatites, in quartzose and micaceous gneiss, and commonly in detrital ...
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 into numerous pigmented spots, resembling freckles, which tend to develop ...
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 available water. Succulents (plants that store water) such as cacti ...
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 in computer design were developed by PARC researchers, including the ...
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 by the battles of Thermopylae, Salamis, and Plataea. His ultimate ...
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 Gcaleka, Ngika, Ndlamba, Dushane, Qayi, Ntinde, and the Gqunkhwebe (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 the Benue-Congo branch of the Niger-Congo language family. Other Southeastern ...
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 forms. His works are typically in ink monochrome, occasionally with ...
Xia Yan: Chinese writer, journalist, and playwright known for his leftist plays and films.
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 and by Lao-Theung (Mon-Khmer) and Tai Neua groups in ...
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) rivers to the south and the Khan River to the ...
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 predominant. Its development during the Qin dynasty (221-206 BC) is ...
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: twice women's world chess champion, from 1991 to 1996 and again from 1999. 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 (1127-1279).
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 (1st-3rd century AD). The characters of xingshu ...
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 Serra Formosa mountain ranges. Formed by several headstreams, principally 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 years. China's wars against the Xiongnu, who were a constant ...