Al-Azhar University, in Cairo, Egypt, one of the world's oldest universities (founded in c.
21st Century Webster's Family Encyclopedia - Alabama to Anderson, Dame Judith
Al Basrah, or Basra (pop. 616,700), second-largest city in Iraq and an important port, lying on the Shatt al Arab River approximately 55 mi (90 km) from the Persian Gulf.
Alabama, state in the southeast United States; bordered by Tennessee in the north, Georgia in the east, Florida and the Gulf of Mexico in the south, and Mississippi in the west. The Appalachian Mountain chain ends in northern Alabama, where it forms a plateau covering a third of the state. The rest of the state is largely lowland plains, the most important of which is the famous Black Belt. Forest…
Alabama, Confederate warship built in England (1862) for use in the U.S.
Alabaster, soft, usually white, semitransparent variety of the mineral gypsum, used to make decorative objects.
Aladdin, boy hero of one of the stories of the Thousand and One Nights, a collection of folk tales from the Middle East preserved in Arabic in the 16th century.
Alain-Fournier (Henri Alban Fournier; 1886–1914), French writer whose one novel, The Wanderer (1913), is the haunting tale of a boy's attempt to rediscover the dreamlike setting of his meeting with a beautiful girl.
Alamo, Spanish mission fortress in San Antonio, Tex.
Alamogordo, (pop. 27,600) town in south-central New Mexico, seat of Otero County.
Alanbrooke, Lord (Alan Francis Brooke, 1st Viscount; 1883–1936), one of the leading British military strategists of World War II and chief of the Imperial General Staff (1941–46).
Alarcón, Pedro Antonio de (1833–91), Spanish regional writer best known for his novel The Three-Cornered Hat (1874).
Alaric, name of 2 Visigothic kings.
Alaska, largest state in the United States, located at the extreme northwest corner of North America, separated from the rest of the continental United States by northwest Canada; bordered by British Columbia and Yukon Territory in the west, the Pacific Ocean in the south, the Bering Sea in the west, and the Arctic Ocean in the north. Alaska's general coastline is 6,640 mi (10,686 km) long,…
Alaska Boundary Dispute, disagreement concerning the demarcation of the border between the Alaska Panhandle and Canada, which arose in 1898 during the Klondike gold rush.
Alaska Highway, road extending 1,422 mi (2,288 km) from Delta Junction, Alaska, to Dawson Creek, British Columbia.
Alaska pipeline, oil pipeline running 789 mi (1,270 km) from Alaska's Prudhoe Bay to the port of Valdez.
Alaskan malamute, strong sled dog developed by the Malemiut Eskimos.
Albéniz, Isaac (1860–1909), Spanish composer and pianist.
Alba, Duke of See: Alva or Alba, Fernando Alvarez de Toledo, Duke of.
Alban, Saint (d. c. 304), first Christian martyr in Britain.
Albania, one of the smallest countries in the Balkans, 210 mi (338 km) long, and less than 100 mi (161 km) wide. The country is mountainous, with isolated fertile basins and a narrow coastal plain. The climate is Mediterranean, but summers can bring prolonged droughts and winters can be harsh. Albania's population is largely Muslim, with a Roman Catholic and Greek Orthodox Christian minorit…
Albany (pop. 874,304), capital of New York since 1797 and seat of Albany County, located on the west bank of the Hudson River about 145 mi (233 km) north of New York City.
Albany Congress, meeting (1754) of 25 representatives from 7 British colonies at Albany, N.Y., aimed at conciliating the Iroquois and improving the common defense of the colonies against the French.
Albany Regency, group of politicians with headquarters in Albany who controlled the New York State Democratic party (1820–54), with the first U.S. political machine.
Albatross, any of 14 species of large, long-winged, gliding, hook-billed seabirds forming the family Diomedeidae.
Albee, Edward Franklin (1928–), U.S. playwright who gained international fame with Who's Afraid of Virginia Woolf? (1962), a penetrating look at contemporary American marriage.
Albert, Carl Bert (1908– ), Oklahoma Democrat, Speaker of the U.S.
Albert I (1875–1934), king of the Belgians(1909–34); nephew and successor of Leopold II.
Albert II (1934– , sixth king of Belgium.
Albert, Prince (Francis Charles Augustus Albert Emmanuel; 1819–61), prince consort of Great Britain, husband of Queen Victoria.
Alberta, westernmost of Canada's Prairie Provinces; bordered by Saskatchewan (in the east), the Northwest Territories (in the north), British Columbia (in the west), and the U.S. state of Montana (in the south). Land and Climate. Alberta is a plateau sloping gradually upward and westward to the Rocky Mountains and the Continental Divide. The south is treeless prairie, the central region is …
Alberti, Leon Battista (1404–72), Italian Renaissance scholar, architect, painter, and art theorist.
Albertus Magnus, Saint (1206?–80), German scholastic philosopher and scientist and teacher of St.
Albigenses, members of a heretical sect that flourished in the 12th and 13th centuries in southern France.
Albino, organism lacking normal pigmentation.
Albright, Ivan Le Lorraine (1897–1983), U.S. painter of microscopically detailed canvases that focus on decay and human dissolution.
Albright, Madeleine Korbel (1937– ), American politician, born in Czechoslovakia.
Albumin, protein that occurs in its most well-known state in the white of an egg.
Albuquerque (pop. 398,500), largest city in New Mexico and seat of Bernalillo County, situated on the Rio Grande.
Alcan Highway See: Alaska Highway.
Alcatraz, rocky island in San Francisco Bay, famous as the site from 1933 to 1963 of a federal maximum security prison, nicknamed “the Rock.” It is now part of the Golden Gate National Recreation Area.
Alchemy, blend of philosophy, mysticism, and chemical processing that originated before the Christian era.
Alcibiades (c. 450–404 B.C.), Athenian statesman and general, nephew of Pericles, and student of Socrates.
Alcindor, Lew See: Abdul-Jabbar, Kareem.
Alcock and Brown, pioneer British aviators, who made the first nonstop flight across the Atlantic Ocean in 1919.
Alcohol, class of compounds containing a hydroxyl group bonded by a carbon atom.
Alcoholics Anonymous (A.A.), international organization founded in 1935 to help people suffering from alcoholism overcome their addictions.
Alcoholism, chronic illness marked by compulsive drinking of alcohol, leading to physical and psychological addiction. Alcohol is a depressant that acts on the central nervous system to reduce anxiety and inhibition. It is a potent and addictive substance that impairs physical coordination, judgment, and perception and, in sufficiently high dosages, can cause unconsciousness or death. Alcohol is n…
Alcott, (Amos) Bronson (1799–1888), U.S. educator, philosopher, and author, father of Louisa May Alcott.
Alcott, Louisa May (1832–88), U.S. author; daughter of Bronson Alcott.
Alcuin, or Albinus (c.
Aldehyde, any of a class of highly reactive organic chemical compounds characterized by a CHO group; especially, acetaldehyde (C2H4O).
Alden, John (1599–1687), one of the leaders of Plymouth Colony.
Alder, any of a genus (Alnus) of shrubs and small trees of the birch family.
Aldridge, Ira Frederick (1805–67), first African American to achieve fame as an actor in the Western Hemisphere.
Aldrin, Buzz (Edwin Eugene Aldrin, Jr.; 1930–), U.S. astronaut.
Aldus Manutius (Teobaldo Mannucci or Manuzio; 1450–1515), Venetian founder of the Aldine Press, whose scrupulous editions of Greek and Roman classics (including the works of Aristotle) advanced Renaissance scholarship.
Aleatory music (from Latin alea, “dice”), music dependent on chance, applied to the post-1950 tendency of composers, such as John Cage, to leave elements in their work to the performer's decision or chance.
Aleichem, Sholem See: Sholem Aleichem.
Aleixandre, Vicente (1898–1984), Spanish poet.
Alembert, Jean le Rond d' (1717–83), French philosopher, physicist, and mathematician, a leading figure in the French Enlightenment, and coeditor with Denis Diderot of the Encyclopedie.
Aleppo (pop. 1,400,000), second-largest city of Syria.
Aleut, native of the Aleutian Islands and western Alaska.
Aleutian Islands, chain of rugged Alaskan islands of volcanic origin, extending westward 1,200 mi (1,900 km) from the Alaska Peninsula and separating the Bering Sea from the Pacific.
Alewife (Alosa pseudoharengus), fish in the herring family.
Alexander, name of 3 Russian tsars. Alexander I (1777–1825) succeeded his father, Paul I, in 1801. In 1805 he joined England and Austria against Napoleon. After French victories Napoleon proposed Franco-Russian domination of Europe, but mutual mistrust came to a head, and Napoleon invaded Russia in 1812. The French were defeated, and in 1815 Alexander formed a coalition with Austria and Pru…
Alexander Archipelago, group of more than 1,100 islands lying along the coastline of the Alaska Panhandle.
Alexander the Great, or Alexander III (356–323 B.C.), king of Macedonia (336–323 B.C.).
Alexander, Grover Cleveland (1887–1950), U.S. baseball player.
Alexander I (1888–1934), king of Yugoslavia from 1921 to 1934.
Alexander III (Orlando Bandinelli; d.1181), pope (1159–81).
Alexander IV (Rodrigo Borgia; 1431–1503), pope (1492–1503).
Alexander of Tunis, 1st Earl (Harold Rupert Leofric George Alexander; 1891–1969), last British-born governor of Canada (1946–52).
Alexandria (pop. 105,000), city and port of entry in Virginia, located on the Potomac River.
Alexandria (pop. 3,295,000), chief port and second-largest city of Egypt.
Alexandrian Library, in antiquity, the greatest collection of manuscripts, first assembled in the 3rd century B.C.
Alexandrite, variety of the mineral chrysoberyl, discovered in 1833 and named for Tsar Alexander II.
Alfalfa, or lucerne (Medicago sativa), legume widely grown for pasture, hay, and silage.
Alfonso XIII (1886–1941), king of Spain from birth until 1931.
Alfred the Great (A.D. 848–899), king of the West Saxons from 871.
Algae, large and diverse group of nonvascular (rootless and stemless) aquatic plants that contain chlorophyll and carry on photosynthesis, including some of the simplest organisms known.
Algebra, branch of mathematics in which relationships between known and unknown quantities are represented symbolically. For a relationship to satisfy the fundamental theorem of algebra it must consist of a finite number of quantities and must have a solution. An example of such a relationship taken from elementary algebra is: axn+bxn−1 +cxn−2+ +z…
Alger, Horatio (1834–99), U.S. author of more than 100 books whose heroes rise from rags to riches through virtue and hard work, including Ragged Dick (1867), Luck and Pluck (1869), and Sink or Swim (1870).
Algeria, country in northwest Africa; bordered by Mauritania, Morocco, and Western Sahara in the west, the Mediterranean Sea in the north, Tunisia and Libya in the east, and Niger and Mali in the south. The Atlas Mountains divide the large country (919,590 sq mi/2,381,741 sq km) into the coastal region (Tell), the steppe, and the desert. Some 75% of the Algerians live in the narrow fertile …
Algiers (pop. 1,483,000), capital, major port, and largest city of Algeria.
Algonquins, or Algonkins, North American Native Americans.
Algren, Nelson (1909–81), U.S. naturalistic novelist, best known for his fiction describing Chicago slum life.
Alhambra (Arabic, “The Red”), 13th-century citadel and palace dominating the city of Granada, the finest large-scale example of Moorish architecture in Spain.
Ali Baba, main character in the story in 1,001 Nights, “Ali Baba and the Forty Thieves.” A poor woodcutter, he discovers that the magic words “Open, Sesame” will open the door to a secret cave containing stolen treasure.
Ali, Muhammad (Cassius Marcellus Clay; 1942–), U.S. boxer.
Alien and Sedition Acts, 4 unpopular laws passed by the U.S.
Alienation, one's estrangement from society and from oneself.
Alimentary canal, passage from the throat to the anus functioning in digestion and absorption of food.
Alinsky, Saul David (1909–72), U.S. pioneer in community organization, known for his early community action work in the Chicago stockyards area (1939).
Alkali, water-soluble compound of an alkali metal that acts as a strong base and neutralizes acids.
Alkaloid, any of a group of organic alkali compounds found in certain plants and fungi, containing carbon, hydrogen, and nitrogen.
Alkalosis, condition wherein the concentration of alkali in the body cells and tissues is higher than normal.
All-American Canal, waterway, completed 1940, that brings water 80 mi (130 km) from the Imperial Reservoir on the Colorado River to irrigate 500,000 acres (200,000 hectares) of the Imperial Valley, Calif.
Allah, Arabic name (al-ilah) for the supreme being, used by the prophet Muhammad to designate the God of Islam.
Allahabad (pop. 806,500), city in the state of Uttar Pradesh, northern India.
Allegheny Mountains, central Appalachian range extending from southwest Virginia into north-central Pennsylvania.
Allegheny River, river in west Pa., important transportation route before the railroads were built.
Allegory, literary work in which characters and concrete images are used to represent abstract philosophical or moral notions.
Allen, Ethan (1738–89), American Revolutionary hero, leader of the Green Mountain Boys of Vermont.
Allen, Richard (1760–1831), first bishop and founder of the African Methodist Episcopal Church.
Allen, Woody (Allen Stewart Konigsberg; 1935–), U.S. comedian, author, and film director.
Allenby, Edmund Henry Hynman, 1st Viscount (1861–1936), British field marshal who directed the campaign that won Palestine and Syria from the Turks in World War I.
Allende Gossens, Salvador (1908–73), Marxist founder of the Chilean Socialist Party, president of Chile (1970–73).
Allentown (pop. 686,688), commercial and industrial city in eastern Pennsylvania, seat of Lehigh County, situated on the Lehigh River about 50 mi (80 km) northwest of Philadelphia.
Allergy, abnormal sensitivity to specific foreign material (an allergen).
Alliance for Progress, program to aid the economic and social development of Latin America, instituted by President John F.
Allies, during World War I, nations bound together in opposition to the Central Powers.
Alligator, either of 2 species of aquatic, carnivorous, lizardlike reptiles (genus Alligator) belonging to the crocodile family.
Alliluyeva, Svetlana (1926–), daughter of Joseph Stalin and his second wife Alliluyeva.
Allopathy, standard form of medical practice, producing a condition incompatible with or antagonistic to the condition being treated; the opposite of homeopathy.
Allotropy, occurrence of an element in 2 or more forms (allotropes) that differ in their crystalline or molecular structure.
Alloy, combination of metals with each other or with nonmetals, such as carbon or phosphorus, and formed by mixing the molten components.
Allspice, dried berry of the pimento, an evergreen tree (Pimenta officinalis) of the myrtle family, used as a spice and for medicinal purposes.
Allston, Washington (1779–1843), U.S. painter.
Alluvial fan, fan-shaped deposit of sediment composed of gravels, sands, and silts.
Alluvium, sand, mud, or other earthly material deposited by rivers and streams, especially in the lower parts of their courses.
Almagro, Diego de See: Pizarro, Francisco.
Almanac, originally, a calendar giving the position of the planets, the phases of the moon, etc., particularly as used by navigators (nautical almanacs), but now any yearbook of miscellaneous information, often containing abstracts of annual statistics.
Almond, tree (Prunus amygdalus) of the rose family, the seed of whose fruit is used as food and flavoring and for medicinal purposes.
Aloe, any of the succulent plants (genus Aloe), of the lily family.
Alpaca (Lama pacos), South American hoofed herbivorous mammal, closely related to the llama.
Alpha Centauri, star 4.3 light-years (about 26 trillion miles) from the earth; only the sun is nearer.
Alpha Orionis See: Betelgeuse.
Alpha particle (α-, or alpha ray), one of the particles emitted in radioactive decay.
Alphabet (from first 2 Greek letters, alpha and beta), set of characters intended to represent the sounds of spoken language.
Alphonsus Liguori, Saint (1696–1787), Italian priest who founded the Congregation of the Most Holy Redeemer (Redemptorist Order), a society of missionary preachers working with the rural poor.
Alps, Europe's largest mountain system, 650 mi (1000 km) long and 30–180 mi (50–290 km) wide.
Alsace-Lorraine (pop. 4,000,000), region in northeast France occupying 5,608 sq mi (14,525 sq km) west of the Rhine.
Alston, Walter Emmons (1911–84), baseball manager.
Altai Mountains, mountain system in central Asia stretching across part of the USSR and the Mongolian People's Republic.
Altamira, cave near Santander, northern Spain, inhabited during the Aurignacian, upper Solutrean, and Magdalenian periods (14,000 B.C.–10,000 B.C.).
Alternating current, electrical signal that reverses direction at regular intervals.
Alternation of generations, in many lower plants and animals, alternation of 2 distinct forms.
Altgeld, John Peter (1847–1902), U.S. political leader and jurist who sought to defend the individual against abuses of governmental power and vested interests.
Altimeter, instrument used for estimating the height of an aircraft above sea level.
Altoona (pop. 130,542), city in Blair County, south-central Pennsylvania, at the foot of the Allegheny Mountains, about 90 mi (145 km) east of Pittsburgh.
Alum, class of double sulfates containing aluminum and such metals as potassium, ammonium, and iron.
Alumina, or aluminum oxide, chemical compound (Al2O3).
Aluminum, chemical element, symbol Al; for physical constants see Periodic Table. Aluminum in the form of its compounds has been used for hundreds of years. Potassium aluminum sulfate, the most common alum, continues to be used in medicine as an astringent, and as a mordant in dyeing. Aluminum was first isolated by Oersted in 1825 although in an impure form. It occurs primarily in the form of comp…
Alva or Alba, Fernando Alvarez de Toledo, Duke of (1507?–82), Spanish general who tyrannized the Netherlands.
Alvarado, Pedro de (1485–1541), Cortés's chief lieutenant in the conquest of Mexico (1519–21) and leader of the force that seized what are now Guatemala and El Salvador (1523–24).
Alvarez, Luis Walter (1911–88), U.S. physicist awarded the 1968 Nobel Prize for physics for work on subatomic particles, including the discovery of transient resonance particles.
Alzheimer's disease, progressive, incurable disease of the brain, the most common cause of premature senility.
AMA See: American Medical Association.
Amadís of Gaul, Spanish romance of chivalry.
Amado, Jorge (1912–), Brazilian novelist, author of The Violent Land (1942), Gabriela, Clove and Cinnamon (1958), and Doña Flor and Her Two Husbands (English, 1969).
Amalfi (pop. 6,000), seaport in the Campania region of Italy, on the Gulf of Salerno, near Naples.
Amalgam, alloy of mercury with another metal, commonly used for tooth fillings.
Amaranth, common name for plants of genus Amaranthus, including pigweed as well as plants grown as cereal and as ornamentals; also, a poetical name for a flower that never fades.
Amarillo (pop. 187,547), largest city and commercial center of the Texas Panhandle.
Amaryllis, family of bulbous-rooted plants with lilylike flowers.
Amasis II (569–525 B.C.), Egyptian pharaoh of the 26th dynasty.
Amateur Athletic Union (AAU), U.S. nonprofit organization, founded in 1888, that promotes and encourages amateur sports.
Amazon River, world's second-longest river (3,900 mi/6,280 km).
Amazons, in Greek mythology, race of warrior women living in the Black Sea area.
Amber, fossilized resin from prehistoric evergreens.
Ambergris, waxy solid formed in the intestines of sperm whales, perhaps to protect them from the bony parts of their squid diets.
Amberjack (genus Seriola), large, elongated fish found in tropical oceans.
Ambrose, Saint (c.
Ambrosia, fabled food of the ancient Greek gods, which conferred immortality on those who partook of it; hence, anything pleasing to the taste or smell.
Ameba, or amoeba, microscopic, one-celled organism that lives in moist earth, water, and parasitically in the bodies of animals.
Amendment, in legislation, change in a bill or motion under discussion, or in an existing law or constitution.
America, the 2 major continents of the Western Hemisphere, North and South America (although the name is sometimes used to mean the United States).
America, patriotic song written in 1832 by the Massachusetts minister, Rev.
America the Beautiful, patriotic song, with words written in 1893 by Katherine Lee Bates, and music by Samuel A.
America First Committee, organization that opposed U.S. involvement in World War II.
America's Cup, international yachting trophy.
American Academy in Rome, institute for independent work and advanced research in the arts, architecture, art history, and archaeology by U.S. artists and scholars in Rome, established in 1894 by the neoclassical architect Charles F.
American Academy and Institute of Arts and Letters, organization to promote literature, music, and the fine arts in the United States.
American Association of Retired Persons (AARP), private, nonprofit organization for people aged 50 and older.
American Automobile Association See: Automobile Association, American.
American Bar Association (ABA), voluntary national organization for members of the U.S. legal profession.
American Booksellers Association (ABA), trade group primarily comprising bookstore owners and publishers, first founded in 1900 in New York City.
American Cancer Society See: Cancer Society of America.
American Civil Liberties Union (ACLU), organization founded in 1920 and dedicated to defending constitutional freedoms in the United States.
American Expeditionary Forces (AEF), name given to the U.S. forces serving in Europe during World War I.
American Federation of Labor and Congress of Industrial Organizations (AFL-CIO), powerful federation of labor unions created in 1955 by the merger of the AFL and CIO. Over 100 constituent unions in the United States, Mexico, Canada, and Panama represent about 15 million members. A national president, secretary-treasurer, and vice-presidents make up the executive council, which enforces policy deci…
American Indian Movement (AIM), civil rights organization in the United States and Canada, founded in 1968 to establish equal rights and improve living conditions of Native Americans.
American Labor Party, New York State left-wing political party (1936–56).
American Legion, organization fostering the welfare, and protecting the rights of United States veterans of World War I, World War II, the Korean War, and the Vietnam War.
American Library Association, society “to extend and improve library service throughout the world.” Founded in Philadelphia (1876) by Melvil Dewey, it is the world's oldest and largest library association and has had great influence on library development in English-speaking countries, as well as in Scandinavia, the Netherlands, and Germany.
American literature, see: United States literature.
American Medical Association (AMA), U.S. federation of state medical organizations.
American Museum of Natural History, institution in New York City founded in 1869 and dedicated to research and public education in anthropology and natural science.
American Party, conservative U.S. political party, originally called the American Independent Party.
American Philosophical Society, oldest surviving U.S. learned society, based in Philadelphia, where it was founded by Benjamin Franklin (1753).
American Red Cross See: Red Cross.
American Revolution See: Revolutionary War in America.
American Samoa, unincorporated U.S. territory in the South Pacific, about 2,300 mi (3,700 km) southwest of Hawaii, with a total area of 76 sq mi (197 sq km).
American Society of Composers, Authors and Publishers (ASCAP), association that serves as a clearinghouse between creators and users of music.
American Society for the Prevention of Cruelty to Animals (ASPCA), organization founded in 1866 to prevent maltreatment of animals by enforcing laws designed to protect them, disseminating information, maintaining animal hospitals, and providing shelters and veterinary facilities.
American System, term used by Henry Clay (1777–1852) for his program of economic nationalism, which provided protective tariffs and internal improvements such as roads and canals.
Americans for Democratic Action (ADA), independent political organization, founded in 1947, that supports liberal policies in government, promoting civil rights and opposing U.S. military involvement in developing countries.
Americium, chemical element, symbol Am; for physical constants see Periodic Table.
Amerigo Vespucci See: Vespucci, Amerigo.
Amethyst, transparent violet or purple variety of quartz, thought to be colored by iron or manganese impurities.
Amherst, Jeffrey Amherst Baron (1717–97), British major-general who helped take Canada from the French.
Amiens (pop. 136,400), city in northern France, capital of the Somme department on the Somme River 80 mi (130 km) north of Paris.
Amin Dada, Idi (1925–), president of Uganda (1971–79).
Amine, chemical compound formed from ammonia (NH3) by replacing 1 or more hydrogen atoms of the ammonia molecule with a corresponding number of hydrogen-carbon groups.
Amino acids, class of organic acids containing a carboxyl group (COOH) and 1 or more (NH2) groups.
Amis, Kingsley (1922–95), English novelist, poet, and critic.
Amish, conservative group of the Mennonite sect, founded by Jacob Ammann in Switzerland in the 1690s.
Amman (pop. 1,573,000), largest city, capital, and commercial and industrial center of the kingdom of Jordan. Industries include food and tobacco processing, textiles, cement, and leatherware. It is a busy transport junction, with good rail and road connections to major Middle Eastern cities and an international airport. Arab refugees from Israel and Israeli-held territories of Jordan have greatly…
Ammann, Othmar Hermann (1897–1965), U.S. engineer.
Ammeter, instrument for measuring amperes of electric current.
Ammonia, chemical compound (NH3), colorless acrid gas.
Amnesia, partial or complete loss of memory.
Amnesty International, organization founded in 1961 to aid political prisoners and others detained for reasons of conscience throughout the world.
Amniocentesis, procedure of sampling the amniotic fluid surrounding a fetus by puncturing the abdomen of the pregnant woman with a very fine, hollow needle.
Amoeba See: Ameba.
Amon, ancient Egyptian deity, sometimes depicted as a ram or a human with a ram's head.
Amos (8th century B.C.), Hebrew prophet; also, a book of the Old Testament containing his life and teachings.
Ampère, André Marie (1775–1836), French mathematician, physicist, and philosopher best remembered for many discoveries in electrodynamics and electromagnetism.
Ampere (amp or A), unit for measuring the rate of flow of an electric current.
Amphetamine, any of a group of stimulant drugs, including Benzedrine and Methedrine, derived from the chemical compound amphetamine (C9H13N).
Amphibian, class of cold-blooded vertebrates, including frogs, toads, newts, salamanders, and caecilians.
Amphibious warfare, coordinated use of land and sea forces to seize a beachhead, an area from which to carry on further military action.
Amphibole, any of a group of silicate minerals with similar chemical compositions and characteristic optical properties.
Amphioxus, or lancet, a small, primitive, fishlike sea animal (genus Branchiostoma), important as a possible descendant of the evolutionary link between invertebrates and vertebrates.
Amphitheater, open edifice built in the Roman Empire for public viewing of contests and spectacles (e.g., the Colosseum in Rome).
Ampicillin, semisynthetic antibiotic that is a derivative of penicillin, used to treat a wide range of bacterial infections.
Amritsar (pop. 708,800), city in Punjab state in northwest India.
Amsterdam (pop. 721,600), capital and largest city of the Netherlands, and one of Europe's great commercial, financial, and cultural centers.
Amtrak, official nickname of the National Railroad Passenger Corp., established by Congress in an effort to halt the deterioration of railroad passenger service.
Amundsen, Roald (1872–1928), Norwegian polar explorer.
Amur, river in northeastern Asia.
Amyotrophic lateral sclerosis, or Lou Gehrig's disease, progressive fatal disease in which there is degeneration of the motor nerve cells of the brain and spine, resulting in progressive muscular atrophy, paralysis, and death from asphyxiation.
Anabaptism, movement advocating baptism of adult believers rather than infants.
Anabolic steroid, any of a group of steroids derived from the male sex hormone testosterone.
Anaconda, semiaquatic subfamily of the boa family.
Anacreon (572–485? B.C.), Greek lyric poet who celebrated wine and love in mellow, simple verses.
Anaheim (pop. 2,410,556), city in Orange County, southern California, southeast of Los Angeles.
Analog computer, computer that operates on data by representing them with physical quantities such as voltages.
Anarchism, political belief that government should be abolished and the state replaced by the voluntary cooperation of individuals and groups.
Anastasia (1901–18?), Russian grand duchess.
Anatomy, study of the structure of plants and animals.
Anaxagoras (500–428 B.C.), Greek philosopher of the Ionian school, resident of Athens, who taught that the elements were infinite in number and that everything contained a portion of every other thing.
Anaximander (611?–547? B.C.), Greek philosopher, first to give a naturalistic, rather than mythological, explanation to natural processes.
Anchorage (pop. 235,000), largest city in Alaska, located in the southern part of the state at the head of Cook Inlet.
Anchovy, small fish of the family Engraulidae, related to the herring family, exported from the Mediterranean for use as a seasoning and garnish.
Ancient civilization, term used to describe history and culture prior to the fall of the Roman Empire.
Andersen, Hans Christian (1805–75), Danish writer, best remembered for his 168 fairy tales.
Anderson, Carl David (1905–91), U.S. physicist who shared the 1936 Nobel Prize in physics for the discovery of the positron (1932).
Anderson, Dame Judith (1898–1992), Australian-born actress who worked in the United States.