D-Day
D-Day, in World War II, June 6, 1944, the day Allied troops landed in Normandy, France, thus launching the last major campaign in Western Europe, under the command of General Eisenhower.
21st Century Webster's Family Encyclopedia - Davis, Henry Gassaway to Diamond
Détente
Détente (French, “relaxation”), name given to the policy of easing tensions between the United States and the USSR that occurred in the late 1960s and 1970s.
Davis Cup
Davis Cup, international men's tennis trophy, first contested in 1900.
Henry Gassaway Davis
Davis, Henry Gassaway (1823–1916), U.S. politician; U.S. senator from West Virginia 1871–83.
Jefferson Davis
Davis, Jefferson (1808–89), president of the Confederate States of America during the Civil War.
John Davis
Davis, John (c. 1550–1605), English navigator and early Arctic explorer.
John William Davis
Davis, John William (1873–1955), U.S. politician and Democratic presidential candidate in 1924, losing to Calvin Coolidge.
Miles Dewey Davis
Davis, Miles Dewey (1926–91), U.S. jazz musician, one of the pioneers of “bebop” in the 1940s and of “cool” jazz, with its restrained, clear sounds, in the 1950s.
Paulina Wright Davis
Davis, Paulina Wright (1813–76), U.S. social reformer who worked for women's rights, campaigning in the 1840s against property laws that made a man the owner of his wife's possessions.
Richard Harding Davis
Davis, Richard Harding (1864–1916), U.S. writer, journalist, and war correspondent.
Samuel Davis
Davis, Samuel (1842–63), Confederate spy, hanged by Union troops for refusing to reveal the source of his information.
Davis Strait
Davis Strait See: Northwest Passage.
Stuart Davis
Davis, Stuart (1894–1964), U.S. abstract painter, illustrator, and lithographer.
Sir Humphry Davy
Davy, Sir Humphry (1778–1829), English chemist who pioneered the study of electrochemistry.
Dawes Act
Dawes Act See: Native Americans.
Charles Gates Dawes
Dawes, Charles Gates (1865–1951), U.S. politician who shared the 1925 Nobel Peace Prize for the plan named after him.
Dawes Plan
Dawes Plan, program presented by Charles Gates Dawes in 1924 to enable Germany to pay off World War I reparations by means of an international loan and mortgages on German industry and railways.
Day
Day, 24-hour period during which the earth completes one rotation on its axis as it rotates around the sun.
Day of Atonement
Day of Atonement See: Yom Kippur.
Clarence Day
Day, Clarence (1874–1935), U.S. writer of essays, sketches, reviews, and stories.
Dorothy Day
Day, Dorothy (1897–1980), U.S. social activist.
Cecil Day-Lewis
Day-Lewis, Cecil (1904–72), English author.
Day lily
Day lily, any of several plants (genus Hemerocallis) of the lily family, growing 3–5 ft (91–150 cm) high.
Dayaks
Dayaks See: Dyak.
Moshe Dayan
Dayan, Moshe (1915–81), Israeli military and political leader.
Dayfly
Dayfly See: Mayfly.
Daylight saving time
Daylight saving time, method of making better use of daylight by setting clocks 1 hour ahead of standard time.
Dayton
Dayton (pop. 951,270), city in southwestern Ohio, seat of Montgomery County.
Jonathan Dayton
Dayton, Jonathan (1760–1824), U.S. soldier and politician, youngest signer of the Constitution (1787).
Daytona Beach
Daytona Beach (pop. 370,712), city in northeastern Florida, 90 mi (145 km) southeast of Jacksonville.
DC
DC See: Electric current.
DDT
DDT (dichloro-diphenyl-trichloroethane), powerful insecticide.
Marguerite Lofft De Angeli
De Angeli, Marguerite Lofft (1889– ), U.S. author and illustrator of children's books.
Prince Louis Victor De Broglie
De Broglie, Prince Louis Victor (1892–1987), French physicist who received the 1929 Nobel Prize in physics for his discovery that the behavior of electrons, like that of light, could be explained in terms of wave motion.
De facto segregation
De facto segregation See: Segregation.
Manuel De Falla
De Falla, Manuel See: Falla, Manuel de.
Lee De Forest
De Forest, Lee (1873–1961), U.S. inventor of the triode (1906), an electron tube with three electrodes that could operate as a signal amplifier as well as a rectifier.
Alcide De Gasperi
De Gasperi, Alcide (1881–1954), Italian statesman.
Charles De Gaulle
De Gaulle, Charles (1890–1970), French soldier and political leader, president 1945–46 and 1958–69.
Hugo De Groot
De Groot, Hugo See: Grotius, Hugo.
De jure segregation
De jure segregation See: Segregation.
Ferenc Deák
Deák, Ferenc (1803–76), Hungarian statesman who negotiated the 1867 Compromise that gave Hungary internal autonomy within Austria-Hungary.
Willem De Kooning
De Kooning, Willem (1904– ), Dutch-born U.S. painter, among the founders of abstract expressionism.
Miguel De la Madrid Hurtado
De la Madrid Hurtado, Miguel (1934– ), Mexican political leader.
Walter John De La Mare
De La Mare, Walter John (1873–1956), English poet and novelist.
Mazo De la Roche
De la Roche, Mazo (1879–1961), Canadian writer best known for a series of 16 novels that chronicle the Whiteoak family from 1852 to 1954.
Juan Ponce De León
De León, Juan Ponce See: Ponce de León, Juan.
Ferdinand Marie De Lesseps
De Lesseps, Ferdinand Marie (1805–94), French engineer and diplomat, builder of the Suez Canal.
Guy De Maupassant
De Maupassant, Guy (1850–93), French writer noted for his short stories.
Agnes George De Mille
De Mille, Agnes George (1909–93), U.S. dancer and choreographer; niece of Cecil B.
Cecil Blount De Mille
De Mille, Cecil Blount (1881–1959), U.S. motion picture producer and director, noted for his use of spectacle; uncle of Agnes George De Mille.
Order of De Molay
De Molay, Order of, international organization of boys and young men between the ages of 13 and 21.
Thomas De Quincey
De Quincey, Thomas (1785–1859), English essayist and critic, author of Confessions of an English Opium Eater (1822), which established his literary reputation.
Vittorio De Sica
De Sica, Vittorio (1901–74), Italian film director.
Willem De Sitter
De Sitter, Willem (1872–1934), Dutch astronomer and cosmologist who examined the age, size, and structure of the universe.
Pierre Jean De Smet
De Smet, Pierre Jean (1801–73), Jesuit missionary to the North American Indians.
Hernando De Soto
De Soto, Hernando (1500?–42), Spanish explorer, discoverer of the Mississippi River.
Antonio José De Sucre
De Sucre, Antonio José See: Sucre, Antonio José de.
Alexis De Tocqueville
De Tocqueville, Alexis See: Tocqueville, Alexis de.
Eamon De Valera
De Valera, Eamon (1882–1975), Irish statesman; prime minister 1932–48, 1951–54, and 1957–58; and president of Ireland 1959–73.
Dame Ninette De Valois
De Valois, Dame Ninette (Edris Stanus; 1898– ), Irish dancer and choreographer.
Bernard Augustine De Voto
De Voto, Bernard Augustine (1897–1955), U.S. journalist and author.
Hugo De Vries
De Vries, Hugo (1848–1935), Dutch botanist who developed the theory of mutation, suggesting that new plant and animal species are the result of sudden transformations that occur spontaneously and are continued for generations.
Jan De Witt
De Witt, Jan (1625–72), Dutch statesman.
DEA
DEA See: Drug Enforcement Administration.
Deacon
Deacon (Greek diakonos, “servant”), assistant to the clergy in a Christian church.
Dead Sea
Dead Sea, salt lake in the Great Rift Valley, on the Israel-Jordan border.
Dead Sea Scrolls
Dead Sea Scrolls, group of Hebrew and Aramaic manuscripts discovered in caves near the northwestern coast of the Dead Sea in 1947 and later.
Deadly nightshade
Deadly nightshade See: Belladonna.
Deadwood
Deadwood (pop. 1,830), city in the Black Hills of South Dakota; the seat of Lawrence County.
Deafness
Deafness, partial or total impairment of the sense of hearing.
Dizzy Dean
Dean, Dizzy (Jay Hanna Dean; 1911–74), U.S. baseball pitcher.
James Dean
Dean, James (1931–55), U.S. actor.
Silas Deane
Deane, Silas (1737–89), U.S. diplomat and first envoy to Europe.
Dearborn
Dearborn (pop. 89,286), city in southeast Michigan, on the River Rouge 10 mi (16 km) west of Detroit.
Henry Dearborn
Dearborn, Henry (1751–1829), U.S. soldier and politician.
Death
Death, complete and irreversible cessation of life in an organism or part of an organism. The moment of death is conventionally accepted as the time when the heart ceases to beat, there is no breathing, and the brain shows no evidence of function. Since it is possible to resuscitate and maintain heart function and to take over breathing mechanically, the brain may suffer irreversible death while &…
Death penalty
Death penalty See: Capital punishment.
Death's-head moth
Death's-head moth, large moth (Acherontia atropos) of the family Sphingidae.
Death Valley
Death Valley, arid valley in southeast California and southern Nevada.
Deathwatch
Deathwatch, any of several beetles belonging to the family Anobiidae.
Michael Ellis DeBakey
DeBakey, Michael Ellis (1908– ), U.S. heart surgeon who developed the pump for the heart-lung machine (1932), devised a new surgical procedure to treat aneurysm, and successfully implanted a mechanical device to help restore a diseased heart (1967).
Debate
Debate, formal and regulated discussion of a given proposition.
Deborah
Deborah, prophet and judge in the Old Testament.
Debrecen
Debrecen (pop. 214,700), city in Hungary, 120 m (193 km) east of Budapest.
Eugene Victor Debs
Debs, Eugene Victor (1855–1926), U.S. labor organizer and socialist political leader.
Debt
Debt, something owed, whether money, services, or goods.
Claude Achille Debussy
Debussy, Claude Achille (1862–1918), French composer.
Peter Joseph William Debye
Debye, Peter Joseph William (1884–1966), Dutch physical chemist chiefly known for the Debye-Hückel theory of ionic solution (1923).
Decalogue
Decalogue See: Ten Commandments.
The Decameron
Decameron, The, collection of 100 stories (written 1348–53) by the Italian author Giovanni Boccaccio.
Decathlon
Decathlon, 10-event track-and-field contest consisting of the 100-meter dash; the 400-meter and 1,500-meter flat races; the 110-meter hurdle race; pole vaulting; discus throwing; shot putting; javelin throwing; and the broad and high jumps.
Decatur
Decatur (pop. 117,206), city in central Illinois located on the Sangamon River and named after the U.S. naval officer Stephen Decatur.
Stephen Decatur
Decatur, Stephen (1779–1820), U.S. naval hero.
Decembrist revolt
Decembrist revolt, unsuccessful uprising against the tsarist government in Russia organized by army officers in December 1825.
Decemvirs
Decemvirs See: Twelve Tables, Laws of the.
Decibel
Decibel (dB), measurement of sound intensity; one-tenth of a bel.
Deciduous tree
Deciduous tree, any of those trees that shed their leaves each year, usually in the fall.
Decimal system
Decimal system, system of computation based on the number 10 (Latin decem). Almost all countries use the decimal system. The system uses 10 numerals — 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 — to represent any number as the sum of powers of 10. The units place indicates multiples of 100 (defined as 1), the tens place indicates multiples of 101, the hundreds place indicates multiples of 102, …
Declaration of Independence
Declaration of Independence, document in which representatives of the 13 American colonies set forth the reasons for their break with Britain. July 4, the day in 1776 on which the Continental Congress adopted the Declaration of Independence, is observed as Independence Day, a U.S. national holiday. A royal proclamation of Aug. 1775 held the colonies to be in a state of rebellion, and in Nov. the B…
Declaration of the Rights of Man and the Citizen
Declaration of the Rights of Man and the Citizen, key philosophical document of the French Revolution, adopted by the National Assembly on August 26, 1789.
Declaratory Act
Declaratory Act See: Revolutionary War in America.
Declination
Declination, in astronomy, one of two coordinates used to specify the position of an object in the sky under the equatorial coordinate system.
Decode
Decode, in information science, the translation or determination of the meaning of a coded set of data.
chemical Decomposition
Decomposition, chemical, reduction of a compound to simpler substances, or to its elemental components.
Decompression sickness
Decompression sickness See: Bends.
Decoration Day
Decoration Day See: Memorial Day.
medals Decorations and orders
Decorations, medals, and orders, awards acknowledging exceptional civil or military service, acts of bravery, and notable achievements in the arts and sciences. In the United States the highest civil decoration is the Presidential Medal of Freedom; the Medal for Merit is also a civil decoration for outstanding services. The highest military decoration “for conspicuous gallantry at the risk …
Decorative arts
Decorative arts, term covering a variety of artistic activities (including woodworking, glass handicrafts, textiles, and metalworking) not traditionally included in the fine arts, which include painting, sculpture, and architecture.
Decoupage
Decoupage (from French découper, “to cut out”), decorative art form in which paper shapes are glued onto other items and covered with coats of varnish.
Deductive method
Deductive method, the process of reasoning by which conclusions are drawn by logical inference from given premises.
John Dee
Dee, John (1527–1628), English philosopher and mathematician accused of sorcery against Queen Mary.
Deed
Deed, legal document transferring the ownership of property.
Deep
Deep, ocean area with a depth in excess of 18,000 ft (5,490 m).
Deer
Deer, any of about 40 species of cloven-hoofed mammals of the family Cervidae, found in Europe, Asia, and the Americas.
Deer fly
Deer fly, insect belonging to the horsefly family, found throughout North America.
John Deere
Deere, John (1804–86), U.S. inventor who developed and marketed the first steel plows.
Deerhound
Deerhound, Scottish breed of dog skilled at hunting deer by sight.
Defenestration of Prague
Defenestration of Prague See: Thirty Years' War.
Department of Defense
Defense, Department of, executive department of the U.S. government responsible for the recruitment, training, organization, and operation of the armed forces. The National Security Act of 1947 superseded the War Department and brought the previously separate departments of the Army, Navy, and Air Force into the National Military Establishment, which was renamed the Department of Defense in 1949. …
Defense mechanism
Defense mechanism, term in psychoanalysis referring to involuntary or unconscious measures adopted by individuals to protect themselves against painful emotions associated with some disagreeable physical or mental situation of frequent occurrence.
Daniel Defoe
Defoe, Daniel (1660?–1731), English author, one of the originators of the English novel.
(Hilaire Germain) Edgar Degas
Degas, (Hilaire Germain) Edgar (1834–1917), French painter and sculptor associated with impressionism.
academic Degree
Degree, academic, title conferred by a university as a recognition of academic competence. Degrees were originally awarded after the candidate had successfully passed a vigorous oral examination, but abuse of this system (particularly in the 18th century at Oxford and Cambridge) led to the gradual adoption of the written examination, at least for the lower (bachelor) degrees. Master's and d…
Dehydrated food
Dehydrated food, food that has been preserved by drying.
Dehydration
Dehydration, removal of water from substances, usually as part of an industrial process or in the preservation of food. Water may be removed in drying chambers through which hot air or gases are passed. A vacuum may be used instead of hot air or gas to evaporate the water at lower temperatures. In chemical processes, gases are dried by passing them through tubes containing drying agents such as ca…
Deism
Deism, religious system developed in the 17th and 18th centuries and championed by such thinkers as Voltaire and Jean Jacques Rousseau.
Thomas Dekker
Dekker, Thomas (c. 1570–c.1632), English dramatist and pamphleteer.
Juan Sebastián Del Cano
Del Cano, Juan Sebastián See: Magellan, Ferdinand.
Ferdinand – Victor – Eugène Delacroix
Delacroix, Ferdinand – Victor – Eugène (1798–1863), French painter whose themes are typical of Romanticism.
Martin Robinson Delany
Delany, Martin Robinson (1812–85), African-American journalist, physician, and army officer.
Robert Delaunay
Delaunay, Robert (1885–1941), French abstract painter.
Delaware
Delaware, Native American tribe of the Algonquian linguistic group that lived in the Delaware River basin area until driven into Ohio in the 18th century by the incursions of colonists and the violence of the French and Indian Wars.
Delaware
Delaware, one of the mid-Atlantic states of the United States; bordered by Maryland in the west and south, Pennsylvania in the north, and the Delaware Bay in the east. Delaware is located on the Delmarva Peninsula, along with parts of Maryland and Virginia. Almost all of the state is part of the Atlantic Coastal Plain, which stretches from New Jersey to southern Florida. Delaware's mean ele…
Delaware Bay
Delaware Bay, inlet of the Atlantic Ocean, bounded by New Jersey on the north and Delaware on the south and west.
Delaware River
Delaware River, major waterway (about 410 mi/660 km long) in the eastern United States.
Max Delbrück
Delbrück, Max (1906–61), German-born U.S. biologist whose discovery of a method for detecting and measuring the rate of mutations in bacteria opened up the study of bacterial genetics.
José Matías Delgado
Delgado, José Matías (1767–1832), Salvadoran priest and patriot.
Delhi
Delhi (pop. 7,206,700), city in northern India, on a plain that has always been strategically important for control of the whole Indian subcontinent.
Delhi sultanate
Delhi sultanate, first Muslim empire in India (1192–1398).
Delian League
Delian League, confederacy of Greek states formed by Athens in 478 B.C. to follow up the Hellenic League's victories against Persia.
(Clément Philibert) Léo Delibes
Delibes, (Clément Philibert) Léo (1836–91), French composer.
Delilah
Delilah, Samson's Philistine mistress in the Old Testament.
juvenile Delinquency
Delinquency, juvenile See: Juvenile delinquency.
Delirium tremens
Delirium tremens, specific condition of confusion, violent shaking, fever, and hallucinations caused by alcohol withdrawal.
Frederick Delius
Delius, Frederick (1862–1934), English composer.
Piero Della Francesca
Della Francesca, Piero See: Piero della Francesca.
Luca Della Robbia
Della Robbia, Luca (1399?–1482), Italian Renaissance sculptor and ceramicist known for his glazed terra cottas.
Dells
Dells See: Dalles.
Vine Deloria Jr.
Deloria, Vine, Jr. (1933– ), Native American leader.
Delphi
Delphi, Greek town located on the lower slopes of Mt.
Delphinium
Delphinium See: Flower; Larkspur.
Delta
Delta, alluvial plain at the mouth of a river, often projecting into a sea or lake and crossed by many water channels.
Deluge
Deluge, in biblical tradition, great flood sent by God to punish humanity, described in Genesis 6–8.
Demand
Demand See: Supply and demand.
Line of Demarcation
Demarcation, Line of See: Line of Demarcation.
Demeter
Demeter, in Greek mythology, the goddess of grain, agriculture, harvest, and fertility.
Democracy
Democracy, system of government under which all members of society have a say in making political decisions, either directly or indirectly. Direct democracy, in which political decisions are made by citizens meeting together, has generally been superceded by representative democracy, under which the population elects members of a decision-making body. Historically, the portion of the population pe…
Democratic-Farmer-Labor Party
Democratic-Farmer-Labor Party See: Farmer-Labor Party.
Democratic Party
Democratic Party, one of the 2 major political parties in the United States. Democrats trace their history back to the Democratic Republican Party (1792) of Thomas Jefferson, who favored popular control of the government. Following the presidential inauguration of Andrew Jackson in 1828, the Democratic Party's base was broadened, with representation from the new West as well as the East. Ja…
Democratic-Republican Party
Democratic-Republican Party, one of the two political parties founded during the first decades of the United States.
Democritus
Democritus (460?–370? B.C.), Greek philosopher who theorized that reality is separated into atoms and the void.
Demography
Demography, study of the distribution, composition, and changes of human populations.
Demosthenes
Demosthenes (384–322 B.C.), Athenian orator and speech writer, best known for his attempts to rouse Athens to resist the encroachment of Philip of Macedon, the father of Alexander the Great.
Jack Dempsey
Dempsey, Jack (William Harrison Dempsey; 1895–1983), U.S. boxer.
Arthur Jeffrey Dempster
Dempster, Arthur Jeffrey (1886–1950), U.S. physicist, developer of the first mass spectrometer (1918), an instrument that measures the mass of atomic nuclei, thereby providing a way to analyze chemical compositions and to distinguish isotopes.
Charles Demuth
Demuth, Charles (1883–1935), U.S. watercolorist and illustrator.
Dendrochronology
Dendrochronology, dating of past events by the study of tree rings.
Deneb
Deneb, or Alpha Cygni, blue-white star, brightest star in the constellation Cygnus and one of the brightest in the sky.
Deng Xiaoping
Deng Xiaoping (1904–97), Chinese Communist leader.
Dengue
Dengue, or breakbone fever, infectious disease characterized by sudden onset of headache, fever, prostration, severe joint and muscle pain, and swollen glands.
Denmark
Denmark, country in northwest Europe consisting of the Jutland Peninsula and 483 islands, of which about 100 are inhabited. The Faeroe Islands, north of Scotland, form a self-governing community within the Kingdom of Denmark; Greenland, the largest island in the world, is a former Danish county that received Home Rule on May 1, 1979. The Jutland Peninsula contains the country's only land fr…
Denominator
Denominator See: Fraction.
Density
Density, ratio of mass of a substance to its volume.
Dental hygiene
Dental hygiene, study and practice of techniques designed to maintain good oral health.
Dentistry
Dentistry, profession that deals with the diagnosis, prevention, and treatment of malformations and diseases affecting the teeth and their related structures, such as gums and oral bones.
Denver
Denver (pop. 513,500), capital and largest city of Colorado, situated in the Rocky Mountains foothills, a mile above sea level.
Deoxyribonucleic Acid
Deoxyribonucleic Acid See: DNA.
Department of
Department of…, Departments of the U.S. government are listed under the key word; for example: Education, U.S.
Depreciation
Depreciation, loss in the value of an asset brought about by age, use, or both.
Depressant
Depressant, any of various drugs that slow physical, mental, or emotional activity.
Depression
Depression, in economics, major decline in business activity involving sharp reductions in industrial production, a rise in bankruptcies, increased unemployment, and a general loss of business confidence.
Depression
Depression, emotional state characterized by sadness, despondency, apathy, and sometimes a deep sense of loss; in psychiatry, clinical depressive illness is more intense and lasts longer than common depressed feelings. Seriously depressed people feel isolated and hopeless and often reproach or blame themselves for exaggerated faults and shortcomings. Fatigue and disturbed sleep are common, while s…
Depth charge
Depth charge, explosive weapon used against submarines and other submerged targets.
André Derain
Derain, André (1880–1954), French painter, one of the original fauves.
Derby
Derby, annual horse race begun at Epsom, England, in 1780 by the 12th earl of Derby.
Kentucky Derby
Derby, Kentucky See: Kentucky Derby.
Dermaptera
Dermaptera See: Earwig.
Dermatitis
Dermatitis, inflammation of the skin, accompanied by moderate to severe itching, with redness, swelling, and sometimes blisters.
Dermatology
Dermatology, subspeciality of medicine concerned with the diagnosis and treatment of skin diseases: alargely visual speciality, but aided by skin biopsy in certain instances.
Dermis
Dermis, or corium, the inner layer of skin beneath the epidermis.
Dervish
Dervish, Muslim mystic, member of a Sufi brotherhood.
DES
DES (diethylstilbestrol), synthetic hormone having the properties of estrogen, the main female sex hormone.
Des Moines
Des Moines (pop. 196,000), capital and largest city of Iowa.
Morarji Desai
Desai, Morarji (1896–1995), Indian political leader.
Desalination
Desalination See: Water.
René Descartes
Descartes, René (1596–1650), French mathematician, scientist, and philosopher, often referred to as “the father of modern philosophy.” A dualist who believed the world was composed of 2 basic substances (matter and spirit), he ignored accepted scholastic philosophy and stated a person should doubt all sense experiences; but if a person can think and doubt, he or she therefore exists.
Deschutes River
Deschutes River See: Oregon.
Desegregation
Desegregation See: Segregation.
Desert
Desert, dry region where life has extreme difficulty surviving.
Operation Desert Shield
Desert Shield, Operation See: Persian Gulf War.
Operation Desert Storm
Desert Storm, Operation See: Persian Gulf War.
Desertion
Desertion, in military law, the abandonment by a soldier of his or her post without the intention of returning.
Design
Design, purposeful arrangement of the elements in a creative work or process.
Despotism
Despotism, absolute government by one person who rules without any constitutional controls.
Josquin Desprez
Desprez, Josquin (1440?–1521), Flemish composer who wrote both secular and sacred music for voice.
Jean Jacques Dessalines
Dessalines, Jean Jacques (1758–1806), first black ruler of Haiti.
Henri-Louis Destouches
Destouches, Henri-Louis See: Céline, Louis-Ferdinand.
Destroyer
Destroyer, small, fast naval warship that evolved in the 1890s out of British torpedo boats.
Detective story
Detective story, popular form of fiction in which a detective solves a crime, usually a murder, by discovering and interpreting clues.
Detergent
Detergent, synthetic chemical that has the same cleaning action as soap but does not form a scum when used in hard water.
Determinism
Determinism, philosophical theory that all events are determined (inescapably caused) by preexisting events that, when considered in the context of inviolable physical laws, completely account for the subsequent events.
Detonator
Detonator, device used to set off a high-explosive charge.
Detroit
Detroit (pop. 1,012,100), Michigan, fifth-largest city in the United States, often called the “Motor City” because it produces over a quarter of all the nation's cars and trucks.
Detroit River
Detroit River, river flowing about 30 mi (48 km) from Lake St.
Deucalion
Deucalion, in Greek mythology, son of the Titan Prometheus.
Deuterium
Deuterium, or heavy hydrogen (D or H2), isotope of hydrogen in which the atomic nucleus contains a neutron as well as a proton, giving it an atomic weight of approximately 2.
Deuteron
Deuteron See: Deuterium.
Deuteronomy
Deuteronomy, fifth book of the Old Testament and last book of the Pentateuch.
Deutschland über Alles
Deutschland über Alles, or “Germany Above All Else,” the German national anthem from 1922 until the division of Germany after World War II.
Deutzia
Deutzia, genus of shrubs having clusters of white, pink, or purple, 5-pet-alled flowers and serated, fuzzy leaves.
Devaluation
Devaluation, reduction of the official value of a currency, the opposite of revaluation.
Developing country
Developing country, term used for any nation with a weak industrial base, a low per capita income, and low gross national product.
Developmental psychology
Developmental psychology, study of behavioral changes that occur during the years from birth to early childhood.
Devil
Devil, in Western religions and sects, chief spirit of evil and commander of lesser evil spirits or demons.
Devil's Island
Devil's Island, small island off the coast of French Guiana, the site of a French penal colony (1852–1951) for political prisoners, among them Alfred Dreyfus.
Devil's paintbrush
Devil's paintbrush, plant with orange-red flowers on a leafless stem up to 28 in (71 cm) long, with oblong leaves growing from the base.
Devil's Triangle
Devil's Triangle See: Bermuda Triangle.
Devil worship
Devil worship, worship of Satan, demons, or evil spirits.
War of Devolution
Devolution, War of (1667–68), conflict between Spain and France over the right of succession to the Spanish Netherlands.
Devonian Period
Devonian Period, fourth period of the Paleozoic Era, beginning about 400 million years ago and lasting 55 million years.
Dew
Dew, layer of water droplets that forms at night on or near the ground.
Dew line
Dew line, acronym for Distant Early Warning line, consisting of 31 radar tracking stations between Alaska and Greenland designed to watch for Soviet air attacks.
Dew point
Dew point, air temperature at which water vapor turns to liquid.
Dewberry
Dewberry, trailing bramble (genus Rubus) with blackberry-like fruit, the only U.S. member of the blackberry group that is cultivated.
Dewey decimal system
Dewey decimal system, devised by Melvil Dewey (1851–1931) for classification of books in libraries, based on the decimal system of numbers.
George Dewey
Dewey, George (1837–1917), U.S. naval hero promoted to admiral of the navy (the highest rank) for his victory at the Battle of Manila Bay and the capture of the Philippines from Spain.
John Dewey
Dewey, John (1859–1952), U.S. philosopher and educator.
Melvil Dewey
Dewey, Melvil (1851–1931), U.S. librarian, inventor of the scheme for organizing library collections known as the Dewey decimal classification system.
Thomas Edmund Dewey
Dewey, Thomas Edmund (1902–71), U.S. lawyer and politician.
Dextrin
Dextrin, chemical substance formed when starch is broken down by the body during digestion.
Dextrose
Dextrose, chemical name for pure glucose sugar.
Dhaka
Dhaka (formerly Dacca; pop. 3,637,900), capital of the independent state of Bangladesh (formerly East Pakistan).
Dharma
Dharma, concept of the eternal truth or law in Hinduism, Buddhism, and Jainism.
Diabetes
Diabetes, or diabetes mellitus, disease characterized by the absence or inadequate secretion of insulin. Normally, sugars and starches (carbohydrates) in food are processed by digestive juices into a form of sugar called glucose, or blood sugar, which is the fuel used by the body. Insulin, a hormone produced by the pancreas, is a major regulator of this process. In the diabetic individual, either …
Sergei Pavlovich Diaghilev
Diaghilev, Sergei Pavlovich (1872–1929), Russian impresario and founder (Paris, 1909) of the Ballets Russes, which inaugurated modern ballet.
Dialectic
Dialectic See: Hegel, Georg Wilhelm Friedrich.
Dialectical materialism
Dialectical materialism See: Materialism; Philosophy.
Dialysis machine
Dialysis machine See: Kidney.
Diamond
Diamond, mineral allotrope (molecular form) of carbon forming colorless cubic crystals (the other forms being graphite and the recently discovered fullerene). Diamond is the hardest known substance, with a Mohs hardness of 10, which varies slightly with the orientation of the crystal. Thus diamonds can be cut only by other diamonds. They do not conduct electricity, but conduct heat extremely well.…