Encyclopædia Britannica Australia -

Encyclopedias since 1768

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relative aperture ... renal capsule

relative aperture: the measure of the light-gathering power of an optical system. It is expressed in different ways according to the instrument involved. The relative aperture for a microscope is called the numerical aperture (NA) and is equal to the sine of ...
relative humidity: ratio of the actual vapour pressure of water in the air to that in air saturated with water vapour; it is often expressed as a percentage. See humidity.
relativistic mass: in the special theory of relativity, the mass that is assigned to a body in motion. In physical theories prior to special relativity, the momentum p and energy E assigned to a body of mass m and velocity v were ...
relativistic mechanics: science concerned with the motion of bodies whose relative velocities approach the speed of light c, or whose kinetic energies are comparable with the product of their masses m and the square of the velocity of light, or mc². Such ...
relativity: wide-ranging physical theories formed by the German-born physicist Albert Einstein. With his theories of special relativity (1905) and general relativity (1916), Einstein overthrew many assumptions underlying earlier physical theories, redefining in the process the fundamental concepts of space, time, matter, ...
relaxation phenomenon: in physics and chemistry, an effect related to the delay between the application of an external stress to a system and its response. It may occur in nuclear, atomic, and molecular systems.
relaxin: a hormone produced by the ovaries during pregnancy that causes pelvic and cervical expansion and relaxation. It inhibits muscular contractions of the uterus that would cause natural abortion of the developing child, stimulates the growth of the glands in the ...
relay: in electricity, electromagnetic device for remote or automatic control of current in one (relay) circuit, using the variation in current in another (energizing) circuit. For example, in a solenoid (q.v.) the core will move when energized to open or close ...
relay race: a track-and-field sport consisting of a set number of stages (legs), usually four, each leg run by a different member of a team. The runner finishing one leg is usually required to pass on a baton to the next runner ...
Reles, Abe: American killer and gangster who became a celebrated police informer in 1940-41.
relic: in religion, strictly, the mortal remains of a saint; in the broad sense, the term also includes any object that has been in contact with the saint. Among the major religions, Christianity, almost exclusively in Roman Catholicism, and Buddhism have ...
relief: in finance, public or private aid to persons in economic need because of natural disasters, wars, economic upheaval, chronic unemployment, or other conditions that prevent self-sufficiency.
relief: in European feudalism, in a form of succession duty paid to an overlord by the heir of a deceased vassal. It became customary on the Continent by the Carolingian period (8th-9th century AD). The sum required was either fixed arbitrarily ...
relief: (from Italian relievare, "to raise"), in sculpture, any work in which the figures project from a supporting background, usually a plane surface. Reliefs are classified according to the height of the figures' projection or detachment from the background. In a ...
relief printing: in art printmaking, a process consisting of cutting or etching a printing surface in such a way that all that remains of the original surface is the design to be printed. Examples of relief-printing processes include woodcut, anastatic printing (also ...
religion: human beings' relation to that which they regard as holy, sacred, spiritual, or divine. Religion is commonly regarded as consisting of a person's relation to God or to gods or spirits. Worship is probably the most basic element of religion, ...
religion, philosophy of: the study, from a philosophical perspective, of the nature of religion and religious belief, including such specific questions as the existence and nature of God and the presence of evil and suffering in the world.
religion, study of: attempt to understand the various aspects of religion, especially through the use of other intellectual disciplines.
religions, classification of: the attempt to systematize and bring order to a vast range of knowledge about religious beliefs, practices, and institutions. It has been the goal of students of religion for many centuries but especially so with the increased knowledge of the ...
religious dress: any attire, accoutrements, and markings used in religious rituals that may be corporate, domestic, or personal in nature. Such dress may comprise types of coverings all the way from the highly symbolic and ornamented eucharistic (Holy Communion) vestments of Eastern ...
religious experience: specific experiences such as wonder at the infinity of the cosmos, the sense of awe and mystery in the presence of the holy, feelings of dependence on a divine power or an unseen order, the sense of guilt and anxiety ...
Religious Science: religious movement founded in the United States by Ernest Holmes (1887-1960). Holmes and his brother Fenwicke were drawn to New Thought teachings and to a belief in the power of the mind for healing and fulfillment of life. In 1926 ...
religious symbolism and iconography: respectively, the basic and often complex artistic forms and gestures used as a kind of key to convey religious concepts and the visual, auditory, and kinetic representations of religious ideas and events. Symbolism and iconography have been utilized by all ...
religious syncretism: the fusion of diverse religious beliefs and practices. Instances of religious syncretism-as, for example, Gnosticism (a religious dualistic system that incorporated elements from the Oriental mystery religions), Judaism, Christianity, and Greek religious philosophical concepts-were particularly prevalent during the Hellenistic period ...
relish: vegetable side dish that is eaten in small quantities with a blander main dish to pique the appetite by its contrasting texture and spicy or piquant taste. Relishes are frequently finely cut vegetables or fruit in sour, sweet-sour, or spicy ...
Relizane: town, northwestern Algeria, near Wadi Mina which is a tributary of the Chelif River. Built near the ruined Roman settlement of Mina, modern Relizane is a typical French-style town of wide streets and parks. It is surrounded by orchards and ...
Relizian Stage: major division of Miocene rocks and time on the Pacific coast of North America (the Miocene epoch began 23.7 million years ago and ended 5.3 million years ago). The Relizian Stage, which overlies the Saucesian Stage and precedes the Luisian ...
rem: unit of radiation dosage (such as from X rays) applied to humans. Derived from the phrase Roentgen equivalent man, the rem is now defined as the dosage in rads that will cause the same amount of biological injury as one ...
Remagen: city, Rhineland-Palatinate Land (state), western Germany. It lies on the left bank of the Rhine River, southeast of Bonn. It originated as the Roman fortress Ricomagnus and has some Roman remains and a 12th-century gate. In World War II it ...
remainder: in Anglo-American law, a future interest held by one person in the property of another, which, upon the happening of a certain event, will become his own. The holder of this interest is known in legal terms as a remainderman.
Remak, Robert: German embryologist and neurologist who discovered and named (1842) the three germ layers of the early embryo: the ectoderm, the mesoderm, and the endoderm. He also discovered nonmedullated nerve fibres (1838) and the nerve cells in the heart (1844) called ...
remanent magnetism: the permanent magnetism in rocks, resulting from the orientation of the Earth's magnetic field at the time of rock formation in a past geological age. It is the source of information for the paleomagnetic studies of polar wandering and continental ...
Remarque, Erich Maria: novelist who is chiefly remembered as the author of Im Westen nichts Neues (1929; All Quiet on the Western Front), which became perhaps the best-known and most representative novel dealing with World War I.
Rembang: city and kabupaten (regency), Jawa Tengah propinsi (Central Java province), Java, Indonesia, located about 100 mi (160 km) northwest of Surabaya. A major port on the Java Sea, it is linked by road and railway with Kudus and Semarang to ...
Rembrandt van Rijn: Dutch painter and printmaker, one of the greatest storytellers in the history of art, possessing an exceptional ability to render people in their various moods and dramatic guises. Rembrandt is also known as a painter of light and shade and ...
remembrancer: English official who from medieval times compiled memorandum rolls and thus "reminded" the barons of the Exchequer (one of the king's courts) of business pending. There were at one time three clerks of the remembrance, with distinct duties, but two ...
Remick, Lee: American actress, known especially for portrayals of sensual, often erotic women in crisis.
Remigius of Reims, Saint: bishop of Reims who greatly advanced the cause of Christianity in France by his conversion of Clovis I, king of the Franks.
Remington, Eliphalet: U.S. firearms manufacturer and inventor.
Remington, Frederic: U.S. painter, illustrator, and sculptor noted for his realistic portrayals of life in the American West.
Remiremont: town, Vosges departement, Franche-Comte region, eastern France. It lies along the Moselle River near the latter's confluence with the Moselotte and is surrounded by wooded heights. Remiremont (Romaraci Mons) is named after St. Romaric, a companion of St. Columban at ...
Remizidae: bird family (order Passeriformes) that contains the penduline tits and, usually, the verdin. Some authorities class the eight species of these birds as a subfamily of the titmouse family, Paridae. Remizids are much like long-tailed tits (Aegithalidae) but have shorter ...
Remizov, Aleksey Mikhaylovich: Symbolist writer whose works had a strong influence on Russian writers before and after the 1917 Revolution.
Remonstrant: any of the Dutch Protestants who, following the views of Jacobus Arminius, presented to the States-General in 1610 a "remonstrance" setting forth their points of divergence from stricter Calvinism. The Remonstrants, assailed on all sides, were expelled from the Netherlands ...
remora: any of 8-10 species of marine fishes of the family Echeneidae (order Perciformes) noted for attaching themselves to, and riding about on, sharks, other marine animals, and oceangoing ships. Remoras adhere by means of a flat, oval sucking disk on ...
Remscheid: city, North Rhine-Westphalia Land (state), northwestern Germany. It lies along the Wupper River, south of Wuppertal, in the heart of the Bergisches Land, a hilly, wooded district in the lower Rhine River valley. Mentioned in the late ...
Remsen, Ira: American chemist and university president, codiscoverer of saccharin.
Renaissance: literally "rebirth," the period in European civilization immediately following the Middle Ages, conventionally held to have been characterized by a surge of interest in classical learning and values. The Renaissance also witnessed the discovery and exploration of new continents, the ...
Renaissance man: an ideal that developed in Renaissance Italy from the notion expressed by one of its most accomplished representatives, Leon Battista Alberti (1404-72), that "a man can do all things if he will." The ideal embodied the basic tenets of Renaissance ...
renal artery: one of the pair of large blood vessels that branch off from the abdominal aorta (the abdominal portion of the major artery leading from the heart) and enter into each kidney. (The kidneys are two bean-shaped organs that remove waste ...
renal capsule: thin membranous sheath that covers the outer surface of each kidney. The capsule is composed of tough fibres, chiefly collagen and elastin (fibrous proteins), that help to support the kidney mass and protect the vital tissue from injury. The number ...