Århus (pop. 271,300), port and Denmark's second largest city.
21st Century Webster's Family Encyclopedia - Arcturus to Augur
Arcturus (Alpha Bootes), brightest and fourth -largest star, orange-red in color.
Ardennes, forested plateau in southeastern Belgium, northern Luxembourg, and northern France.
Arecjuipa (pop. 634,800), city in southern Peru, capital of Arequipa department.
Arendt, Hannah (1906–75), German-born U.S. political philosopher.
Areopagus, small hill northwest of the Acropolis in Athens, where the supreme council of the city passed judgment on matters of state, religion, and morality.
Ares, in Greek mythology, the god of war.
Argentina, second-largest country in South America (1,072,157 sq mi/2,776,889 sq km). Only Brazil is larger. Argentina borders on the Atlantic Ocean in the southeast; Uruguay, Brazil in the east, Paraguay in the northeast, Bolivia in the north, and Chile in the west. The Andes Mountains form a natural border with Chile. The Gran Chaco region, in the north, is an extensive forested plain. Also in t…
Argon, chemical element, symbol Ar; for physical constants see Periodic Table.
Argonaut, or paper nautilus, small marine animal (genus Argonauta), a cephalopod which is native to the Mediterranean and other warm seas.
Argonauts, heroes of Greek mythology who set sail in the ship Argo under Jason to find the Golden Fleece.
Argonne National Laboratory, nuclear-power research center 25 mi (40 km) south of Chicago.
Argus, or Argos, in Greek mythology, (1) the designer of the Argonauts' ship Argo; (2) the old dog who died after recognizing his master, Odysseus, returning in disguise to his home in Ithaca after an absence of 19 years; (3) the monster called Panoptes (the all-seeing) because of the great number of eyes in his head and over his body.
Ariadne, in Greek mythology, daughter of Minos, king of Crete.
Arianism, 4th-century Christian heresy founded in Alexandria by the priest Arius.
Arias Sánchez, Oscar (1941–), Costa Rican politician.
Ariosto, Ludovico (1474–1533), Italian poet best remembered for the epic Orlando Furioso (1532), which continued the Roland legend, depicting the hero as a love-torn knight.
Aristarchus of Samos (310–230 B.C.), Alexandrian Greek astronomer who recognized that the sun is larger than the earth.
Aristides (530?–468? B.C.), called the Just, Athenian politician and general, a founder of the Delian League.
Aristocracy (from Greek aristos, “the best,” and kratos, “rule”), originally, the ruling of a state by its best citizens in the interest of all; used by the philosophers Plato and Aristotle in this sense.
Aristophanes (450–385 B.C.), comic dramatist of ancient Greece.
Aristotle (384–322 B.C.), Greek philosopher, one of the most influential thinkers of the ancient world.
Arithmetic (Greek arithmos, “number”), science of numbers.
Ariyoshi, Sawako (1931–84), Japanese writer of short stories, murder mysteries, and historical novels that explore the culture, traditions, social structure, and domestic problems of classical and modern Japan.
Arizona, state in the southwest United States; bordered by Utah in the north, New Mexico in the east, Mexico in the south, and, across the Colorado River, Nevada and California in the west. The Colorado Plateau to the north contains the Grand Canyon, the Painted Desert, the Petrified Forest, and Monument Valley. A mountain chain extends northwest to southeast through the Basin and Range Region, wh…
Ark, biblical vessel Noah built for protection from the great flood (Genesis 6–9); also, the Ark of the Covenant, the sacred chest of the Hebrews representing God's presence (Exodus 25).
Ark of the Covenant, wooden chest, overlaid inside and out with gold, containing the original Ten Commandments.
Arkansas, state in the south-central United States; bordered by Tennessee and Mississippi (east), Louisiana (south), Texas and Oklahoma (west), and Missouri (north). Arkansas' major rivers include the Arkansas River, which bisects the state, and the Ouachita. The Ozark Plateau, or Mountains, in the northwest and Ouachita Mountains in the west-central part of the state make up the highland r…
Arkansas River, the longest tributary of the Mississippi-Missouri system, rising in the central Colorado Rocky Mountains and flowing SE 1,459 mi (2,339 km) to join the Mississippi near Greenville, Miss.
Arkwright, Sir Richard (1732–92), English industrialist and inventor of cotton carding and spinning machinery.
Arlington National Cemetery, U.S. national cemetery in northern Virginia, established in 1864.
Armada, fleet of armed ships, in particular Spain's “Invincible Armada,” 130 ships carrying 30,000 men sent by Philip II in 1588 to seize control of the English Channel for an invasion of England.
Armadillo, armored mammals (family Dasypodidae) of the order Edentata, native to warm regions of the Western Hemisphere.
Armageddon, according to the Bible, the site of the world's last great battle, in which the powers of good will destroy the forces of evil (Revelation 16:16).
Armagnac, hilly farming area of southwestern France noted for its brandy.
Armenia, republic in western Asia, bordered by Turkey, Azerbaijan, and Georgia. Armenia is mountainous and the landscape extends from subtropical lowland to snow-covered peaks. Small mountain pastures provide rich grazing for sheep and cattle, and the valleys are fertile when irrigated. The climate is continental, with cold winters and hot summers. The population is mainly Armenian (90%) wi…
Armor, protective body covering used in armed combat.
Armory Show, officially the International Exhibition of Modern Art, the first show of its kind in the United States, held at the 69th Regiment Armory, New York City, Feb.-Mar. 1913.
Arms control See: Disarmament; Strategic Arms Limitation Talks.
Armstrong, Anne Legendre (1927-), U.S. political figure.
Armstrong, Edwin Howard (1890–1954), U.S. electronic engineer who developed the feedback concept for amplifiers (1912), invented the superheterodyne circuit used in radio receivers (1918), and perfected FM radio (1925–39).
Armstrong, Henry (1912–88), U.S. boxer.
Armstrong, Louis “Satchmo” (1900–71), U.S. jazz musician renowned as a virtuoso trumpeter and singer.
Armstrong, Neil Alden (1930– ), U.S. astronaut, first human to set foot on the moon.
Armstrong, Samuel Chapman (1839–93), U.S. educator and philanthropist.
Armstrong, William Howard (1914-), U.S. author.
Army, land fighting force of a nation; more narrowly, a large unit of ground forces under a single commander.
Army, Department of the, division of the U.S.
Army, U.S., branch of U.S. armed forces organized to fight any war, local or global, conventional or atomic.
Army War College, senior educational institution of the U.S.
Army worm, any of several species of voracious caterpillars that travel in masses, causing severe crop damage; especially the common army worm (Pseudaletia unipuncta).
Arnhem (pop. 134,700), capital of the province Gelderland in the east Netherlands, located on the north bank of the Rhine River, about 60 mi (100 km) east of Rotterdam.
Arnica, genus of plants of which the flowers and rootstock are used for medicinal purposes.
Arno River, river in central Italy, about 150 mi (241 km) long.
Arnold, Benedict (1741–1801), general and traitor in the American Revolution.
Arnold of Brescia (c. 1100–50), Italian religious reformer and political activist who strongly opposed the temporal power of the pope.
Arnold, Henry “Hap” Harley (1886– 1950), pioneer aviator and U.S.
Arnold, Matthew (1822–88), English poet and literary critic.
Arpád, dynasty of Hungarian rulers founded by Arpád (c.840–907), around whose life countless heroic legends are woven.
Arp, Jean, or Hans (1887–1966), French sculptor, painter, and poet.
Arraignment, appearance of a person in a court of law to plead guilty or not guilty to legal charges.
Arrau, Claudio (1903–91), Chilean pianist.
Arrest, taking into custody of a person believed to have committed a crime.
Arrhythmia, irregularity in rhythm of the heartbeat, either in time or force.
Arrow See: Archery.
Arrow, Kenneth Joseph (1921– ), U.S. economist, former professor at Harvard and adviser on economic affairs to the U.S. government.
Arrowroot, plant (genus Maranta) native to warm, humid regions of the Western Hemisphere; also, form of starch from the rhizomes (underground stems) of the arrowroot plant and various other tropical plants.
Arsenic, chemical element, symbol As; for physical constants see Periodic Table.
Art and the arts, skill of making or doing. The term can be used to define useful arts (beautiful objects that have functional value), decorative arts (beautiful objects that exist for their own sake), liberal arts (the study of humanities), applied arts (such as architecture), language arts (the related skills of reading, writing, speaking, and spelling), and graphic arts (such as printmaking and…
Art deco, style of design popular in the United States and Europe from the late 1920s through the 1930s.
Art nouveau, late 19th-century art movement that influenced decorative styles throughout the West.
Artagnan, Charles d' (1620–73), French soldier whose name was immortalized by the swashbuckling character d'Artagnan in Alexandre Dumas's The Three Musketeers.
Artemis, in Greek mythology, virgin goddess of the hunt.
Arteriosclerosis, generic term for disease of the arteries in which their walls become thickened and rigid, and blood flow is hindered, often resulting in heart disease or stroke.
Artery, blood vessel that carries blood away from the heart to other parts of the body.
Artesian well, well in which water rises under hydrostatic pressure above the level of the aquifer (water-bearing layer of rock) in which it has been confined.
Arthritis, inflammation of a joint, usually accompanied by pain and frequently by changes in structure.
Arthropod, largest and most diverse phylum of the animal kingdom, containing insects, millipedes, centipedes, crustacea, arachnida, and king crabs.
Arthroscopy, technique used to visualize the interior of a joint.
Arthur, Chester Alan (1830–86), 21st president of the United States. Arthur was vice president under James A. Garfield and became president on Garfield's assassination. Probably his most important accomplishment as president was his support for reforms in the federal civil service system. Arthur was the son of a Baptist minister and schoolteacher from Northern Ireland. He graduated f…
Arthur, King, legendary British king, subject of tales and poems dating back to the 7th century.
Artichoke (Cynara scolymus), tall, thistlelike perennial plant of the composite family; also, its globe-shaped flower bud, the heart and spiny bracts of which are eaten as a vegetable.
Articles of Confederation, first written constitutional structure for the United States, drafted in 1776–77, but ratified by 13 states only in 1781.
Articles of War, code adopted in 1775 by the Continental Congress to guide administration of justice and discipline in the Continental Army.
Artificial insemination, introduction of sperm into the vagina by means other than copulation.
Artificial intelligence (AI), use of computers to perform functions normally associated with human intelligence, such as reasoning, learning, and self-improvement.
Artificial limb, device to replace missing hands, feet, arms, or legs.
Artificial organ, mechanical device designed to assume the functions of an organ of the body, particularly during surgical procedures.
Artificial sweetener, synthetic substance, usually saccharin, aspartame, or acesulfame-K, used in place of sucrose (table sugar) to sweeten food and beverages.
Artificial turf, grasslike product of nylon or other synthetic material used to carpet athletic playing fields and also used in outdoor landscaping.
Artigas, José Gervasio (1764–1850), Uruguayan military leader who championed the cause of national independence.
Artillery, once the term for all military machinery, now applied to guns too heavy to be carried by one or two soldiers.
Aruba (pop. 70,000), island off the Venezuelan coast, part of the Netherlands Antilles, about 19 mi (30.6 km) long and 4 mi (6.4 km) wide.
Arum, common name of certain plants of the Araceae family, including lily, philodendron, and elephant's ear.
Aryan (Sanskrit, “noble” or “ruler”), name originally applied to peoples who invaded the Indus Valley in India about 1500 B.C.
Asafetida, foul-smelling substance extracted from the roots of an Asian herb.
Asante See: Ashanti.
Asbestos, name for various fibrous minerals, such as chrysotile, used as noncombustible material.
Asbury, Francis (1745–1816), first Methodist bishop in the United States, elected 1784.
Asbury Park (pop. 17,015), Atlantic Coast resort in eastern New Jersey, founded in 1871 as a religious meeting place and incorporated as a city in 1897.
ASCAP See: American Society of Composers, Authors and Publishers.
Ascension, The, in Christian belief, the bodily ascent of Jesus Christ into heaven on the 40th day after his resurrection.
Asceticism, self-denial or self-mortification in the interest of heightening spiritual powers.
Asch, Sholem (1880–1957), Yiddish novelist and playwright.
ASCII, acronym for American Standard Code for Information Interchange, the character code used for representing information by most non-IBM equipment.
Asclepius, in Greek mythology, the god of healing, who became so skilled that he attempted to resurrect the dead, thus angering Zeus, who struck him dead with a thunderbolt.
Ascorbic acid See: Vitamin.
Asexual reproduction See: Reproduction.
Asgard, or Aesir, in Norse mythology, the realm of the gods.
Ash, tree or shrub (genus fraxinus) of the olive family.
Ash Wednesday, 40th weekday before Easter Sunday and the first day of the Christian fast of Lent.
Ashanti, or Asante, region of central Ghana, in West Africa, inhabited by the people of the same name.
Ashbery, John (1927–), U.S. poet of unconventional style, whose poems are experimental, fragmentary, and dreamlike.
Ashcan School, or “The Eight,” name given to a group of painters in New York City, formed in 1908, because they painted everyday aspects of city life.
Ashcroft, Dame Peggy (1907–91), British stage actress.
Ashe, Arthur (1943–93), U.S. tennis player.
Asheville (pop. 174,821), city and resort in the Appalachian Mountains, western North Carolina, seat of Buncombe County, near the Great Smoky Mountains National Park and the Blue Ridge Parkway.
Ashkenazim, Jews whose medieval ancestors lived in Germany.
Ashland (pop. 27,064), city in northern Kentucky on the Ohio River, the seat of Boyd County.
Ashton, Sir Frederick (1906–88), British dancer and choreographer.
Ashurbanipal, or Assurbanipal (d. 626? B.C.), last of the great kings of Assyria, ruled 669–633 B.C. over an empire that included Babylonia, Syria, and Palestine.
Asia, world's largest continent, more than 17,139,000 sq mi/44,390,000 sq km (nearly 1/3 of the earth's land), with about 3.1 billion people (more than 60% of the world population). It extends from the Arctic Ocean to the Indian Ocean, and from the Pacific Ocean to the Mediterranean. Its traditional border with Europe is formed by the Ural Mountains. Asia is separated from Afr…
Asia Minor, peninsula in southwestern Asia including most of modern Turkey, mountainous and surrounded on 3 sides by the Black and Mediterranean seas, bounded on the east by the upper Euphrates River.
Asimov, Isaac (1920–92), prolific (almost 400 books) U.S. author, biochemist, and educator, known for his science fiction works, including the Foundation trilogy (1951–53, 1982) and The Gods Themselves (1972), as well as for his many popular works on various fields of science and general knowledge.
Asmara (pop. 275,400), capital of Eritrea.
Asoka (d.232 B.C.), third emperor of the Maurya dynasty of India, whose acceptance of Buddhism as the official religion of his vast empire contributed to that faith's predominance in Asia.
Asp, Egyptian cobra (Naja haja) of the family Elapidae, an extremely poisonous snake up to 7 ft (2 m) in length.
Asparagus, garden vegetable (Asparagus officinalis) of the lily family, a perennial plant cultivated for its tender stalks.
Aspartame See: Artificial sweetener.
Aspasia (5th century B.C.), learned woman from Miletus, mistress of the Athenian statesman Pericles, by whom she had a son, Pericles the Younger.
Aspen (pop. 3,678), town in south-central Colorado and seat of Pitkin County.
Aspen, deciduous tree of the poplar genus widely distributed in north temperate regions, commercially valued as a source of pulp and matches.
Asphalt, tough black material made of heavy hydrocarbons and used in road paving, roofing, and canal and reservoir lining.
Asphodel, perennial herbaceous plant (genera Asphodelus and Asphodeline) of the lily family, with white or yellow flowers along the stalk.
Asphyxiation, complex of symptoms resulting from a lack of oxygen or excess of carbon dioxide in the lungs.
Aspidistra, perennial plant (Aspidistra lurida) of the lily family, with sturdy leaves, once a widely grown houseplant.
Aspirin, or acetylsalicylic acid, effective painkiller that reduces fever and inflammation.
Asquith, Herbert Henry, 1st Earl of Oxford and Asquith (1852–1928), English prime minister, 1908–16.
Assad, Hafez al- (1930–), president of Syria since 1971.
Assam (pop. 22,414,300), state in India located in the extreme northeast of the country and connected to the rest of India by West Bengal.
Assault and battery, any threatening physical act that reasonably causes another person to fear bodily harm or offensive contact.
Assaying, method of chemical analysis used to determine the presence, absence, or quantity of a particular component of ores or alloys, used since the 2nd millennium B.C.
Assembler, computer program that converts symbolic code into binary object (machine) code for execution.
Assemblies of God, largest of the Protestant Pentecostal denominations in the United States.
Assembling, in computer terminology, automatic process by which a computer converts a symbolic-language program into a machine language, usually on an instruction-by-instruction basis.
Assembly language, hardware-dependent symbolic language used in computers, usually characterized by a one-to-one correspondence of its statements with machine-language instructions.
Assembly line, production line of equipment, machinery, and workers along which successive operations are performed until the final product is complete.
Assessment, value of property (most commonly homes, shops, and offices) for purposes of taxation, or the process of determining this value.
Assignment, in law, transfer of rights, especially intangible property rights: insurance policies, certificates of corporate shares, and rights to monies due or to become due.
Assimilation, the process by which food is appropriated as nourishment for the body, following digestion and absorption.
Assiniboia, 2 former, distinct districts of Canada, one formed by the Hudson's Bay Company around the Red River in 1835, incorporated in Manitoba (1870), the other, a section of the Northwest Territories (1882–1905), in the southern portion of present-day Alberta and Saskatchewan.
Assiniboine, Sioux tribe of the North American plains who left the Yanktonai Sioux to spread out from Canada across the northwestern United States.
Assisi, Francis of See: Francis of Assisi, Saint.
Associated Press (AP), oldest and one of the largest U.S. news agencies (gatherers and distributors of news).
Association, in psychology, mental linking of one item with others, by similarity, contiguity, opposition, or other principles.
Associationism, psychological school holding that the sole mechanism of human learning consists in the permanent association in the intellect of impressions that have been repeatedly presented to the senses.
Assumption of the Virgin, Roman Catholic belief (declared as official dogma by Pope Pius XII in 1950) that the Virgin Mary was “assumed into heaven body and soul” at the end of her life.
Assurbanipal See: Ashurbanipal.
Assyria See: Babylonia and Assyria.
Astaire, Fred (Frederick Austerlitz; 1899–1988), U.S. dancer, choreographer, and actor.
Astarte, Phoenician goddess of love and fertility, corresponding to Babylonian Ishtar and Greek Aphrodite.
Astatine, chemical element, symbol At; for physical constants see Periodic Table.
Aster (genus Aster), also known as Michaelmas or Christmas daisy, perennial plant with blue, purple, white, or red flowers that bloom in autumn.
Asteria, in Greek mythology, daughter of Coeus, the Titan, and mother of Hecate.
Asteroid, planetoid, or minor planet of irregular shape, orbiting the sun.
Asthenosphere, the worldwide “soft layer” underlying the rigid lithosphere, located some 43.5–155 mi (70–250 km) below the earth's surface.
Asthma, reversible obstruction of the airways that compromises the respiratory system.
Astigmatism, defect of vision caused by irregular shaping in the cornea or lens.
Aston, Francis William (1877–1945), British physicist and chemist.
Astor, name of a prominent U.S. family involved in fur trading, real estate, and finance, as well as in U.S. and British politics.
Astrakhan (pop. 510,000), capital of Astrakhan Oblast in the RF.
Astringent, substance that causes the organic tissues and canals of the body to contract, thereby checking or diminishing excessive discharges.
Astroarcheology See: Archeoastronomy.
Astrolabe, astronomical instrument dating from ancient times, used to measure the altitude and movements of celestial bodies.
Astrology, system of beliefs based on the theory that movements of celestial bodies influence human events, which can therefore be predicted.
Astronaut, term for U.S. test pilot or scientist chosen by NASA to crew space flights.
Astronautics, or astronautical engineering, scientific study of the principles of space flight, including astrodynamics, space communications, propulsion theory, astrobiology, astrogeology, and the design analysis of spacecraft.
Nineteenth-century astronomers analyzed the composition of stars and wondered what causes them to burn. In the early 20th century, Albert Einstein announced his theory that mass and energy are equivalent, and the idea of nuclear power was introduced. It is now known that the sun produces energy by nuclear fusion. The branch of astronomy called cosmology seeks to find out how the universe originate…
Astrophysics, science dealing with the physical laws governing the nature of celestial objects and events, enabling astronomers to formulate theories of stellar evolution and cosmology.
Asturias, Miguel Ángel (1899–1974), Guatemalan writer and diplomat.
Asunción (pop. 456,000), capital and largest city of Paraguay.
Aswan High Dam, one of the world's largest dams, built on the Nile River in Egypt (1960–70), located 4 mi (6.4 km) south of the 1902 Aswan dam.
Asylum, sanctuary or place of refuge; an institution for receiving and maintaining persons suffering certain physical or mental diseases or defects.
Asyut (pop. 2,223,000), city in the eastern central region of Egypt, on the left bank of the Nile, about 250 mi (402 km) south of Cairo.
Atacama Desert, arid plateau extending from central Chile to southern Ecuador, some 600 mi (966 km) long and 2,000 ft (610 m) high.
Atahualpa (1500–33), last Inca emperor of Peru.
Atalanta, in Greek mythology, beautiful, swift-footed huntress who promised to marry any suitor who outran her, but to kill any she could beat.
Atatürk, Kemal (Mustafa Kemal; (1881–1938), founder of modern Turkey.
Atavism, inheritance by an individual organism of characteristics not shown by its parental generation.
Ataxia, impaired muscular coordination resulting in unsteady gait, difficulty in fine movements, and speech disorders.
Atchison, city in northeastern Kansas, on the Missouri River.
Atchison, David Rice (1807–86), U.S.
Athabasca, river and lake in northern Alberta and Saskatchewan, Canada.
Athanasius, Saint (c.297–373), early Christian theologian and Greek Father of the Church.
Atharva-Veda See: Vedas.
Atheism, denial of the existence of God, distinguished from agnosticism, which holds that the existence of God cannot be proved or disproved but does not necessarily take any position on belief.
Athena (Pallas Athena), in Greek mythology, goddess of wisdom, war, and peace, who sprang fully grown from the head of Zeus.
Athens (pop. 748,100), capital and largest city of Greece, in east central Greece.
Atherosclerosis See: Arteriosclerosis.
Athlete's foot, popular name for a fungus infection of any area of the skin of the feet or toes, causing inflammation and itching.
Athlone, Alexander Augustus Frederick William Alfred George Cambridge, 1st Earl of (1874–1957), British army officer and member of the royal family.
Atlanta (pop. 394,900), capital and largest city of Georgia, seat of Fulton County.
Atlanta, Battle of See: Civil War, U.S.
Atlantic Charter, declaration of common objectives signed by U.S.
Atlantic City (pop. 40,200), seaside resort and convention center in southeast New Jersey.
Atlantic Intracoastal Waterway, shallow, sheltered water route extending 1,134 mi (1,825 km) along the Atlantic seaboard from Norfolk, Va., to Key West, Fla., and serving pleasure craft and light shipping.
Atlantic Ocean, world's second-largest ocean (c.31.8 million sq mi/82.3 million sq km), separating the Americas from Europe and Africa.
Atlantic Provinces, the 4 Canadian provinces of Newfoundland, New Brunswick, Nova Scotia, and Prince Edward Island, the last 3 of which are sometimes called the Maritime Provinces.
Atlantic States, those states of the U.S. south of New England bordering on the Atlantic Ocean or closely relying on it economically.
Atlantis, in Greek mythology, an island in the western sea (Atlantic Ocean?).
Atlas, in Greek mythology, a titan.
Atlas Mountains, mountain system of northwest Africa.
Atmosphere, spheroidal envelope of gas and vapor surrounding a planet, retained by gravity. The composition of the earth's atmosphere and most of its physical properties vary with altitude. About 75% of the total mass of the atmosphere and 90% of its water vapor are contained in the troposphere, the lowest zone, which extends from the earth's surface to an altitude of a…
Atoll, low-lying oval or circular coral reef, enclosing a lagoon, most prevalent in the western Pacific Ocean.
Atom, classically, one of the minute, indivisible, homogeneous particles of which physical objects are composed; in 20th-century science, the name given to a relatively stable package of matter that is itself made up of at least 2 subatomic particles, and that defines an element. Every atom consists of a tiny nucleus (containing positively charged protons and electrically neutral neutrons) with wh…
Atom smasher See: Particle accelerator.
Atomic bomb See: Nuclear bomb.
Atomic clock, precise electric device for measuring time, indirectly controlled by atomic or molecular vibration.
Atomic energy See: Nuclear energy; Fission; Nuclear energy.
Atomic fusion See: Fusion; Nuclear energy.
Atomic number See: Atom.
Atomic particle See: Atom.
Atomic reactor See: Nuclear reactor.
Atomic theory See: Atom.
Atomic weight, mean of the masses of all the various isotopes of a given element.
Atonement, in Christian theology, reconciliation of humanity with God through the sacrificial death of Christ.
Atreus, in Greek mythology, king of Mycenae and the father of Agamemnon and Menelaus.
Atrium, unroofed or partially roofed interior court of a Roman house, with rooms extending around it; also, entrance court of early Christian churches.
Atrophy (Greek, “not nourished”), decrease in size and function or wasting away of any organ, tissue, or part of the body as a result of disease, malnutrition, decreased work, or normal processes of growth or body function.
Atropine, crystalline alkaloid contained in plants such as jimsonweed and deadly nightshade (belladonna), used in many gastrointestinal and ophthalmic preparations.
Atsina See: Gros Ventre.
Attachment, seizure of property by legal process, to prevent a defendant from disposing of disputed property before trial, and to guarantee payment of any judgment against him or her.
Attainder, loss of civil rights (strictly, rights of ownership and disposition of property) by someone outlawed or sentenced to death.
Attar, fragrant, essential oil, often made from various species of roses, that forms a valuable perfume.
Attila (A.D. 406?–453), king of the Huns, who claimed domination from the Alps and the Baltic to the Caspian Sea.
Attlee, Clement Richard, 1st Earl (1883–1967), British politician and prime minister (1945–51).
Attorney, one who is legally appointed in the place of another as an agent to transact any business for him or her; especially a lawyer.
Attorney general, chief law officer of a nation (in Canada also called minister of justice).
Attucks, Crispus (c. 1723–70), U.S. patriot of African and Native American parentage who was the first of 5 men to die in the Boston Massacre.
Atwood, Margaret (1939–), Canadian poet and novelist.
Auckland (pop. 889,200), chief port, largest city, naval base, and industrial center of New Zealand, capital of Auckland province on North Island.
Auckland Islands, group of uninhabited islands, of volcanic origin, lying in the southern Pacific Ocean about 200 mi (320 km) south of New Zealand.
Auden, W(ystan) H(ugh) (1907–73), Anglo-American poet and major influence in 20th century literature.
Audiology, science of hearing; particularly, the study of hearing disorders and rehabilitation of individuals with hearing defects.
Audit, in accounting, examination of accounts or dealings with money or property, performed by persons not involved in the preparation of the accounts.
Audubon, John James (1785–1851), U.S. artist and ornithologist famous for his paintings of North American birds, reproduced in Birds of America (1827–38).
Auerbach, Red (Arnold Auerbach; 1917–), U.S. basketball coach who led the Boston Celtics to 9 championships in 10 years (1957; 1959–66).
Augsburg (pop. 258,300), capital of the administrative district of Swabia in Bavaria, Germany, on the Lech River about 35 mi (56 km) from Munich.
Augsburg Confession, statement of Lutheran beliefs presented to the Diet of Augsburg on June 25, 1530.
Augur, in ancient Rome, official who derived signs (auguries) concerning future events from the flight or other actions of birds, certain appearances in quadrupeds, lightning, or other unusual occurrences.