Encyclopædia Britannica Australia -

Encyclopedias since 1768

0-9

acid dye ... Acropolites, George

acid dye: any bright-coloured synthetic organic compound whose molecule contains two groups of atoms-one acidic, such as a carboxylic group, and one colour-producing, such as an azo or nitro group. Acid dyes are usually applied in the form of their sodium salts, ...
acid halide: neutral compound that reacts with water to produce an acid and a hydrogen halide. Acid halides are ordinarily derived from acids or their salts by replacement of hydroxyl groups by halogen atoms. The most important organic acid halides are the ...
acid rain: form of precipitation containing a heavy concentration of sulfuric and nitric acids. The term is also commonly applied to snow, sleet, and hail that manifest similar acidification. Such precipitation has become an increasingly serious environmental problem in many areas of ...
acid-base catalysis: acceleration of a chemical reaction by the addition of an acid or a base, the acid or base itself not being consumed in the reaction. The catalytic reaction may be acid-specific (acid catalysis), as in the case of decomposition of ...
acid-base reaction: a type of chemical process typified by the exchange of one or more hydrogen ions, H⁺, between species that may be neutral (molecules, such as water, H₂O; or acetic acid, CH₃CO₂H) or electrically charged (ions, such as ammonium, NH₄⁺; hydroxide, ...
acidosis: abnormally high level of acidity, or low level of alkalinity, in the body fluids, including the blood. Acidosis may be respiratory or metabolic in origin. The former may result from excess retention of carbon dioxide because of faulty oxygen-carbon dioxide ...
Acireale: town and episcopal see, Catania provincia, eastern Sicily, Italy, on terraces above the Ionian Sea at the foot of Mount Etna, 7 miles (11 km) northeast of Catania. Known as Aquilia by the Romans, the town was called Reale by ...
Acis: in the Greek mythology of Ovid, the son of Faunus (Pan) and the nymph Symaethis. He was a beautiful shepherd of Sicily, the lover of the Nereid Galatea. His rival, Polyphemus the Cyclops, surprised them together and crushed him to ...
Acker, Kathy: American novelist whose writing style and subject matter reflect the so-called punk sensibility that emerged in the 1970s.
Ackerley, J.R.: British novelist, dramatist, poet, and magazine editor known for his eccentricity.
Ackerman, Diane: American writer whose works often reflect her interest in natural science.
Ackermann, Konrad Ernst: actor-manager who was a leading figure in the development of German theatre.
Ackermann, Louise-Victorine: French poet who is best-known for works characterized by a deep sense of pessimism.
Ackroyd, Peter: British novelist, critic, biographer, and scholar whose technically innovative novels present an unconventional view of history.
Acmeist: member of a small group of early-20th-century Russian poets reacting against the vagueness and affectations of Symbolism. It was formed by the poets Sergey Gorodetsky and Nikolay S. Gumilyov. They reasserted the poet as craftsman and used language freshly and ...
acne: any inflammatory disease of the sebaceous, or oil, glands of the skin. There are some 50 different types of acne. In common usage, the term acne is frequently used alone to designate acne vulgaris, or common acne, probably the most ...
Acoemeti: monks at a series of 5th- to 6th-century Byzantine monasteries who were noted for their choral recitation of the divine office in constant and never interrupted relays. Their first monastery, at Constantinople, was founded in about 400 by St. Alexander ...
acolyte: (from Greek akolouthos, "server," "companion," or "follower"), in the Roman Catholic church, a person is installed in a ministry in order to assist the deacon and priest in liturgical celebrations, especially the eucharistic liturgy. The first probable reference to the ...
Acoma: Indian pueblo, Valencia county, west-central New Mexico, U.S. The pueblo lies 55 miles (89 km) west-southwest of Albuquerque and is known as the "Sky City." Its inhabitants live in terraced dwellings made of stone and adobe atop a precipitous sandstone ...
Aconcagua River: river in central Chile. It rises in the northwestern foothills of Mount Aconcagua of the Andes Mountains and flows westward from the Argentine border area through Valparaiso region to enter the Pacific Ocean north of the city ...
Aconcagua, Mount: mountain in Argentina. It is commonly regarded as the highest summit in the Western Hemisphere, rising 22,834 feet (6,959 metres) above sea level. Aconcagua lies in the Southern Andes, its peak being in Mendoza province in northwestern Argentina, but its ...
aconite: any member of two genera of perennial herbs of the buttercup family (Ranunculaceae): Aconitum, consisting of summer-flowering poisonous plants (see monkshood), and Eranthis, consisting of spring-flowering ornamentals (see winter aconite).
Acontius: in Greek legend, a beautiful youth of the island of Ceos. During the festival of Artemis at Delos, Acontius saw and loved Cydippe, a girl of a rich and noble family. He wrote on an apple the words "I swear ...
Acontius, Jacobus: advocate of religious toleration during the Reformation whose revolt took a more extreme form than that of Lutheranism.
acorn and nut weevil: any of about 45 species of weevils that make up the subfamily Curculioninae of the family Curculionidae (order Coleoptera). The insects have extremely long and slender snouts, which in females can be almost twice the body length. Eggs are deposited ...
acorn worm: any of the soft-bodied invertebrates of the class Enteropneusta, phylum Hemichordata. The front end of these animals is shaped like an acorn, hence their common name. The "acorn" consists of a proboscis and a collar that may be used to ...
acosmism: in philosophy, the view that God is the sole and ultimate reality and that finite objects and events have no independent existence. Acosmism has been equated with pantheism, the belief that everything is God. G.W.F. Hegel coined the word to ...
Acosta, Joaquin: Colombian scientist, historian, and statesman who sought to preserve knowledge of his country's early history.
Acosta, Jose de: Jesuit theologian and missionary to the New World, chiefly known for his Historia natural y moral de las Indias, the earliest survey of the New World and its relation to the Old. His works, missionary and literary, mark the end ...
Acosta, Uriel: freethinking rationalist who became an example among Jews of one martyred by the intolerance of his own religious community. He is sometimes cited as a forerunner of the renowned philosopher Benedict de Spinoza.
acouchy: either of two species of South American rodents that resemble the small tropical-forest-dwelling hoofed animals of Africa and Asia (see royal antelope; chevrotain). Weighing 1 to 1.5 kg (2.2 to 3.3 pounds), acouchys are 30 to 39 cm (12 to ...
acoustic impedance: absorption of sound in a medium, equal to the ratio of the sound pressure at a boundary surface to the sound flux (flow velocity of the particles or volume velocity, times area) through the surface. In analogy to electrical circuit ...
acoustic interferometer: device for measuring the velocity and absorption of sound waves in a gas or liquid. A vibrating crystal creates the waves that are radiated continuously into the fluid medium, striking a movable reflector placed accurately parallel to the crystal source. ...
acoustic neuroma: benign tumour on the vestibulocochlear nerve (also called acoustic nerve) near its point of entry into the inner ear. The tumour, though benign, may spread into the brain cavity if not detected in its first stages. Early symptoms include mild ...
acoustic trauma: physiological changes in the body caused by sound waves. Sound waves cause variations in pressure, the intensity of which depends upon the range of oscillation, the force exerting the sound, and the distribution of waves.
acoustics: the science concerned with the production, control, transmission, reception, and effects of sound. The term is derived from the Greek akoustos, meaning "hearing."
acquired character: in biology, modification in structure or function acquired by an organism during its life, caused by environmental factors. With respect to higher organisms, there is no evidence that such changes are transmissible genetically-the view associated with Lamarckism-but, among protozoans and ...
acquittal: in criminal law, acknowledgment by the court of the innocence of the defendant or defendants. Such a judgment may be made by a jury in a trial or by a judge who rules that there is insufficient evidence either for ...
Acrasieae: class name for cellular slime molds (division Myxomycophyta). The class contains a single order, Acrasiales, and about a dozen species. The vegetative phase of these slime molds consists of amoeba-like cells (myxamoebas) that group together ultimately to form a fruiting ...
Acre: westernmost estado ("state") of Brazil. Acre covers the southwesternmost part of Brazil's Hileia (Hylea), the forest zone of the Amazon River basin. Bounded north by Amazonas state, it has western and southern frontiers with Peru and southeastern ...
acre: unit of land measurement in the British Imperial and United States Customary systems, equal to 43,560 square feet, or 160 square rods. One acre is equivalent to 0.4047 hectares (4,047 square metres). Derived from Middle English aker (from Old English ...
Acre River: river, chiefly in western Brazil, rising on the Peruvian border, along which it continues eastward to form part of the Brazil-Bolivia border. Turning north at Brasileia, the remainder of its 400-mi (645-km) course flows in a north-northeasterly direction, through the ...
acriflavine: dye obtained from coal tar, introduced as an antiseptic in 1912 by the German medical-research worker Paul Ehrlich and used extensively in World War I to kill the parasites that cause sleeping sickness. The hydrochloride and the less irritating base, ...
Acrisol: one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO). Acrisols form on old landscapes that have an undulating topography and a humid tropical climate. Their natural vegetation is woodland, which in some ...
acrobatics: (Greek: "to walk on tip-toe," or "to climb up"), the specialized and ancient art of jumping, tumbling, and balancing, often later with the use of such apparatus as poles, one-wheel cycles, balls, barrels, tightropes, trampolines, and flying trapezes.
acrocephalosyndactyly: congenital malformation of the skeleton, affecting the skull, hands, and feet, first described by the French pediatrician Eugene Apert. The head is shortened front-to-back and appears pointed (acrocephaly) because of premature closing of the cranial sutures between the individual bones ...
acrocyanosis: uneven reddish-blue discoloration of the hands caused by spasms in arterioles (small arteries) of the skin. Less commonly the feet are affected. The fingers, or toes, are usually cold and sweat copiously. The condition may be the result of an ...
acrolith: statue, especially ancient Greek, in which the trunk of the figure was of wood and the head, hands, and feet of marble. The wood was either gilded or covered by real or metal drapery. Acroliths are known from the descriptions ...
acromegaly: growth and metabolic disorder characterized by enlargement of the skeletal extremities. It is the result of overproduction of pituitary growth hormone (somatotropin) after maturity, caused by a tumour of the pituitary gland. Acromegaly is often associated with the abnormal growth ...
acropolis: (Greek: "city at the top"), central, defensively oriented district in ancient Greek cities, located on the highest ground and containing the chief municipal and religious buildings. Because the founding of a city was a religious act, the establishment of a ...
Acropolites, George: Byzantine scholar and statesman, the author of Chronike Syngraphe ("Written Chronicle"), a history of the Byzantine Empire from 1203 to 1261. He also played a major diplomatic role in the attempt to reconcile the Greek and Latin ...