Encyclopædia Britannica Australia -

Encyclopedias since 1768

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diapason ... dichlorobenzene

diapason: (from Greek dia pason chordon: "through all the strings"), in medieval music, the interval, or distance between notes, encompassing all degrees of the scale-i.e., the octave. In French, diapason indicates the range of a voice and is also the word ...
diapause: spontaneous interruption of the development of certain animals, marked by reduction of metabolic activity. It is typical of many insects and mites, a few crustaceans and snails, and perhaps certain other animal groups. This period of suspended development is an ...
Diapensiales: order of dicotyledonous flowering plants comprising the family Diapensiaceae, with seven genera of small, evergreen shrubs and basally woody herbs found in Arctic and alpine (high elevation) habitats of Europe, Asia, and the eastern United States.
diaper: in architecture, surface decoration, carved or painted, generally composed of square or lozenge shapes but also of other simple figures, each of which contains a flower, a spray of leaves, or some such device. The pattern is repetitive and is ...
diaphragm: dome-shaped, muscular and membranous structure that separates the thoracic (chest) and abdominal cavities in mammals; it is the principal muscle of respiration.
diapir: (from Greek diapeirein, "to pierce"), geological structure consisting of mobile material that was forced into more brittle surrounding rocks, usually by the upward flow of material from a parent stratum. The flow may be produced by gravitational forces (heavy rocks ...
diarrhea: abnormally swift passage of waste material through the large intestine, with consequent discharge of loose feces from the anus. Diarrhea may be accompanied by cramping. The disorder has a wide range of causes. It may, for example, result from bacterial ...
Diarthrognathus: genus of extinct, advanced mammal-like reptiles found as fossils in Late Triassic terrestrial deposits in southern Africa (the Triassic Period lasted from 245 to 208 million years ago). Diarthrognathus was contemporaneous with a host of other mammal-like reptiles but is ...
diary: form of autobiographical writing, a regularly kept record of the diarist's activities and reflections. Written primarily for the writer's use alone, the diary has a frankness that is unlike writing done for publication. Its ancient lineage is indicated by the ...
Dias, Bartolomeu: Portuguese navigator and explorer who led the first European expedition to round the Cape of Good Hope (1488), opening the sea route to Asia via the Atlantic and Indian oceans. He is usually considered to be the greatest of the ...
Dias, Dinis: Portuguese navigator and explorer, one of the sea captains sent by Prince Henry the Navigator to open trade with countries of Africa, the Middle East, and India.
Diaspora: the dispersion of Jews among the Gentiles after the Babylonian Exile; or the aggregate of Jews or Jewish communities scattered "in exile" outside Palestine or present-day Israel. Although the term refers to the physical dispersal of Jews throughout the world, ...
diaspore: white or grayish, hard, glassy aluminum oxide mineral (HAlO₂) that is associated with corundum in emery and is widespread in laterite, bauxite, and aluminous clays. It is abundant in Hungary, South Africa, France, Arkansas, and Missouri. Diaspore is dimorphous with ...
diastereoisomer: either member of a pair of substances that differ with respect to the configurations of their molecules (i.e., stereoisomers) and that lack a mirror-image relationship (i.e., are not enantiomorphs). An example is the pair consisting of either of the two ...
diastole: in the cardiac cycle, period of relaxation of the heart muscle, accompanied by the filling of the chambers with blood. Diastole is followed in the cardiac cycle by a period of contraction, or systole (q.v.), of the heart muscle. Initially ...
diastrophism: large-scale deformation of the Earth's crust by natural processes, which leads to the formation of continents and ocean basins, mountain systems and rift valleys, and other features by mechanisms such as lithospheric plate movement, volcanic loading, or folding.
Diatessaron: the four New Testament Gospels compiled as a single narrative by Tatian (q.v.) about AD 150. It was the standard Gospel text in the Syrian Middle East until about AD 400, when it was replaced by the four separated Gospels. ...
diathermy: form of physical therapy in which deep heating of tissues is accomplished by the use of high-frequency electrical current. American engineer and inventor Nikola Tesla in 1891 first noted that heat resulted from irradiation of tissue with high-frequency alternating current ...
diatom: any member of the algal division or phylum Bacillariophyta (about 16,000 species) found floating in all the waters of the Earth. Diatoms may be either unicellular or colonial. The silicified cell wall forms a pillbox-like shell (frustule) composed of overlapping ...
diatomaceous earth: light-coloured, porous, and friable sedimentary rock that is composed of the siliceous shells of diatoms, unicellular aquatic plants of microscopic size. It occurs in earthy beds that somewhat resemble chalk, but it is much lighter than chalk and will not ...
diatonic: in music, originally, one of the three tetrachords basic to ancient Greek theory; more generally, any stepwise arrangement of the seven "natural" pitches forming an octave devoid of chromatic alterations, in particular the major and minor scales that evolved from ...
Diatryma: extinct, giant flightless bird found as fossils in Early Eocene rocks in North America and Europe (the Eocene Epoch lasted from 57.8 to 36.6 million years ago). Diatryma grew to a height of about 2 14 metres (7 feet). Its ...
Diavolo, Fra: Italian brigand chief who repeatedly fought against the French occupation of Naples; he is celebrated as a popular guerrilla leader in folk legends and in the novels of the French writer Alexandre Dumas pere.
Diaz de La Pena, Narcisse-Virgile: French painter and lithographer of the group of landscape painters known as the Barbizon school, who is distinguished for his numerous Romantic depictions of the forest of Fontainebleau and his landscape fantasies with mythological figures.
Diaz de Solis, Juan: chief pilot of the Spanish navy and one of the first explorers to enter the Rio de la Plata estuary in South America.
Diaz del Castillo, Bernal: Spanish soldier and author, who took part in the conquest of Mexico.
Diaz Ordaz, Gustavo: president of Mexico from 1964 to 1970.
Diaz, Abby Morton: American novelist and writer of children's literature whose popular and gently humorous work bespoke her belief in children's innate goodness.
Diaz, Armando: Italian general who became chief of staff during World War I.
Diaz, Porfirio: soldier and president of Mexico (1877-80, 1884-1911), who established a strong centralized state that he held under firm control for more than three decades.
diazepam: tranquilizing drug used in the treatment of anxiety and as an aid in preoperative and postoperative sedation. Diazepam also is used to treat skeletal muscle spasms. It belongs to a group of chemically related compounds (including chlordiazepoxide) called benzodiazepines, the ...
diazo compound: any of a class of organic substances that have as part of their molecular structure the characteristic atomic grouping
diazonium salt: any of a class of organic compounds that have the molecular structure
Dib, Mohammed: Algerian novelist, poet, and playwright, known for his early trilogy on Algeria, La Grande Maison (1952; "The Big House"), L'Incendie (1954; "The Fire"), and Le Metier a tisser (1957; "The Loom"), ...
Diba al-Hisn: settlement and port town, on the eastern (Gulf of Oman) coast of the Oman Promontory of the Arabian Peninsula. It is situated on Diba Bay and is surrounded by mountains. The town and its locality are part of two countries: ...
Dibang Valley: region, northeastern Arunachal Pradesh state, eastern India. The region is located in the Great Himalayan Mountain Range, with its northern and eastern reaches fronting Tibet. The Mishmi Hills, a southward extension of the Himalayas, compose most of the northern part ...
dibatag: (Ammodorcas clarkei), slender north African antelope, family Bovidae (order Artiodactyla), that lives alone or in small groups in grass and thorn brush. The dibatag is a long-legged, long-necked animal with rounded ears, small hooves, and a long, thin black tail ...
Dibdin, Charles: composer, author, actor, and theatrical manager whose sea songs and operas made him one of the most popular English composers of the late 18th century.
Dibdin, Thomas Frognall: English bibliographer who helped to stimulate interest in bibliography by his own enthusiastic though often inaccurate books, by his share in founding the first English private publishing society, and by his beautifully produced catalog of Lord Spencer's library (which collection ...
Dibelius, Martin: German biblical scholar and pioneer of New Testament form criticism (the analysis of the Bible's literary forms).
Dibiasi, Klaus: Austrian-born Italian diver who dominated the platform event from the late 1960s to the mid-1970s, winning three Olympic gold medals. He was the first Italian to win a gold medal in a swimming or diving event.
Dibner, Bern: American engineer and historian of science.
Dibon: ancient capital of Moab, located north of the Arnon River in west-central Jordan. Excavations conducted there since 1950 by the archaeologists affiliated with the American School of Oriental Research in Jerusalem have uncovered the remains of several city walls, a ...
Dibrugarh: town, northeastern Assam state, northeastern India. Dibrugarh is situated along the Brahmaputra River and is an important commercial centre, a port, and a rail terminus. Its industries include tea processing and rice and oilseed milling. The Assam Medical College, a ...
Dicaearchus: Greek Peripatetic philosopher of Messina in Sicily, a pupil of Aristotle and a scholar of wide learning who influenced such people as Cicero and Plutarch. He spent most of his life in Sparta. Neglecting systematic philosophy, he cultivated special branches ...
Dicaeidae: songbird family, of the order Passeriformes, including the diamondbird and flowerpecker (qq.v.) groups.
dicastery: a judicial body in ancient Athens. Dicasteries were divisions of the Heliaea from the time of the democratic reforms of Cleisthenes (c. 508-507 BC), when the Heliaea was transformed from an appellate court to a court with original jurisdiction. Each ...
dice: small objects (polyhedrons) used as implements for gambling and the playing of social games. The most common form of die is the cube, with each side marked with from one to six small dots (spots). The spots are arranged in ...
Dicentra: genus of flowering plants of the fumitory family (Fumariaceae) that includes such popular wild garden representatives as bleeding heart, Dutchman's-breeches, and squirrel corn (qq.v.).
Dicey, Albert Venn: British jurist whose Lectures Introductory to the Study of the Law of the Constitution (1885) is considered part of the British constitution, which is an amalgam of several written and unwritten authorities. For this treatise, which is ...
dichlorobenzene: any of three isomeric substances produced by the chlorination of benzene or chlorobenzene in the presence of iron(III) chloride. All three are colourless, denser than water, and insoluble in it. They belong to the family of organic halogen compounds.