Skip this Advertisement

A-Z Browse

  • Igboid languages
    a language cluster that constitutes a subbranch of the Benue-Congo branch of the Niger-Congo language family. There are nearly 20 million speakers of Igboid languages in southeastern Nigeria. In the early years of the 20th century an attempt to develop an artificial form of Igbo called Union-Igbo, based on four Igbo dialects, was not successful. Later a standa...
  • IGC
    ...into two epochs, the Pleistocene and the Holocene, with the Pleistocene (and therefore the Quaternary) understood to have begun some 1.8 million years ago. In 1948 a decision was made at the 18th International Geological Congress (IGC) in London that the base of the Pleistocene Series should be fixed in marine rocks exposed in the coastal areas of Calabria in southern Italy. As ratified by......
  • IGC (government of Iraq)
    Ṣaddām and his regime were driven from power in the spring of 2003 by a U.S.-led military coalition. On April 26, 2004, the Iraqi Governing Council announced a new national flag, its design consisting of four unequal horizontal stripes from top to bottom of white, blue, yellow, and blue and with a light blue crescent centred on the white stripe. The flag, almost universally......
  • IGCR (international organization)
    ...for resettlement, and an extensive tracing service to find lost relatives. It also assumed the responsibilities for the legal protection and resettlement of refugees previously carried out by the Intergovernmental Committee on Refugees. It was succeeded by the Office of the United Nations High Commissioner for Refugees (q.v.). ...
  • IgD (biochemistry)
    ...are grouped into five classes according to their constant region. Each class is designated by a letter attached to an abbreviation of the word immunoglobulin: IgG, IgM, IgA, IgD, and IgE. The classes of antibody differ not only in their constant region but also in activity. For example, IgG, the most common antibody, is present mostly in the blood and tissue fluids,......
  • igdlu (dwelling)
    temporary winter home or hunting-ground dwelling of Canadian and Greenland Inuit (Eskimos). The term igloo, or iglu, from Eskimo igdlu (“house”), is related to Iglulik, a town, and Iglulirmiut, an Inuit people, both on an island of the same name. The igloo, usually made from blocks of snow and dome-shaped, is used only in the area between the Mackenzie River...
  • IgE (biochemistry)
    ...are grouped into five classes according to their constant region. Each class is designated by a letter attached to an abbreviation of the word immunoglobulin: IgG, IgM, IgA, IgD, and IgE. The classes of antibody differ not only in their constant region but also in activity. For example, IgG, the most common antibody, is present mostly in the blood and tissue fluids, while IgA is...
  • “Igennem nat og trængel” (song by Ingemann)
    ...Master Comes”), Julen har bragt velsignet bud (“Christmas Has Brought Blessed Tidings”), and Igennem nat og trængsel (“Through the Night of Doubt and Sorrow”), well known in English translation. To a lesser extent, he is also remembered for his historical novels....
  • IGF-1 (biochemistry)
    Growth hormone may act directly on tissues, but much of its effect is mediated by stimulation of the liver and other tissues to produce and release insulin-like growth factors, primarily insulin-like growth factor 1 (IGF-1; formerly called somatomedin). The term insulin-like growth factor is derived from the ability of high concentrations of these factors to mimic the action of......
  • IGF-2 (biochemistry)
    There are two insulin-like growth factors, insulin-like growth factor 1 (IGF-1) and insulin-like growth factor 2 (IGF-2). The name reflects the fact that they have insulin-like actions in some tissues, but in fact they are far less potent than insulin in decreasing blood glucose concentrations, and their fundamental action is to stimulate growth. These two factors, despite the similarity of......
  • IgG (biochemistry)
    Antibodies are grouped into five classes according to their constant region. Each class is designated by a letter attached to an abbreviation of the word immunoglobulin: IgG, IgM, IgA, IgD, and IgE. The classes of antibody differ not only in their constant region but also in activity. For example, IgG, the most common antibody, is present mostly in the blood and tissue fluids,......
  • Iggerot Aḥad Haʿam (work by Aḥad Haʿam)
    ...a leading role in eliciting from the British government its Balfour Declaration of 1917, a document supporting a Jewish homeland in Palestine. His last years were spent in Palestine, editing his Iggerot Aḥad Haʿam, 6 vol. (1923–25; “Letters of Aḥad Haʿam”). Further letters, principally from the last phase of his life, and his memoirs were....
  • Iggy and the Stooges (American rock group)
    American band of the late 1960s and early 1970s that helped define punk music. Both with the Stooges and in his subsequent solo career, Iggy Pop had a far-reaching influence on later performers. The principal members were Iggy Pop (original name James Jewel Osterberg; b. April 21, 1947Ypsilanti, Mich., U.S....
  • Ighil Izane (Algeria)
    town, northwestern Algeria, near Wadi Mîna which is a tributary of the Chelif River. Built near the ruined Roman settlement of Mina, modern Relizane is a typical French-style town of wide streets and parks. It is surrounded by orchards and gardens, and 30,000 acres (12,000 hectares) are irrigated with waters from the Wadi Mîna via the Bakhadda Dam. Cereals, grapes,...
  • Ightham Mote (England, United Kingdom)
    ...the 14th century the manor-house plan was clearly defined, with private living apartments and service rooms at opposite ends of the great hall and with battlements, gatehouse, and moat—as at Ightham Mote, Kent. Ockwells Manor in Berkshire is a typical timber-framed manor house built in the 15th century without defensive elements....
  • Igilgili (Algeria)
    town and roadstead port, northeastern Algeria, on the Mediterranean seacoast and the western edge of the Collo Kabylie region. The city of Jijel, originally a Phoenician trading post, passed successively to the Romans (as Igilgili), the Arabs, and, in the 16th century, to the pirate Khayr ad-Dīn (Barbarossa). It remained a corsair stronghold until captured by the French i...
  • Igilium (island, Italy)
    mountainous, volcanic islet of the Tuscan Archipelago, in the Tyrrhenian Sea, opposite Mount Argentario, on the west coast of Italy. The island rises to 1,634 feet (498 m) and has an area of 8 square miles (21 square km). Wine is produced, and there is considerable offshore fishing. The village of Giglio Castello, surrounded by medieval walls, and the bathing resort of Campese a...
  • Iglau (Czech Republic)
    city, south-central Czech Republic. It lies in the Bohemian-Moravian Highlands, along the Jihlava River. From about 1240, its prosperity rested on its silver mines. A royal mint operated there from about 1260, and a codified town mining law (Ius Regale Montanorum) served as a model for other central European mining laws. Hussite Utraquists and representatives of the Council of B...
  • Iglau, Compact of (Bohemian history)
    ...the grant of communion in both kinds as a basis of settlement. The Utraquist nobles annihilated the protesting Taborites at the Battle of Lipany (May 30, 1434) and made peace with the council by the Compact of Iglau (July 5, 1436), which conceded them communion in both kinds and reunited them with the Roman Catholic church. The Utraquist nobles extracted far better terms from Sigismund as the.....
  • Iglesia (mountain pass, South America)
    ...between them are the high passes of Mount Espinacito (16,000 feet) and Mount Patos (12,825 feet). South of Anconcagua the passes include Pircas (16,960 feet), Bermejo (more than 10,000 feet), and Iglesia (13,400 feet). Farther north the passes are more numerous but higher. The peaks of Mounts Bonete, Ojos del Salado, and Pissis surpass 20,000 feet....
  • Iglesia Filipina Independiente (church, Philippines)
    independent church organized in 1902 after the Philippine revolution of 1896–98 as a protest against the Spanish clergy’s control of the Roman Catholic Church. Cofounders of the church were Isabelo de los Reyes y Florentino, author, labour leader, and senator, who was imprisoned during the revolution for his criticism of Spanish clergy and government officials in the Philippines, and...
  • Iglesia ni Cristo (Filipino church)
    the largest entirely indigenous Christian church in the Philippines. Its members assert that the early Christian church was restored in God’s chosen nation, the Filipinos, when Felix Manalo launched this church in 1914. Rapid growth after 1945 produced some 600,000 members by the late 20th century, imposing chapels throughout the nation, and a wealthy centralized organization. Strong discip...
  • Iglesia ni Kristo (Filipino church)
    the largest entirely indigenous Christian church in the Philippines. Its members assert that the early Christian church was restored in God’s chosen nation, the Filipinos, when Felix Manalo launched this church in 1914. Rapid growth after 1945 produced some 600,000 members by the late 20th century, imposing chapels throughout the nation, and a wealthy centralized organization. Strong discip...
  • Iglesias (Italy)
    town and episcopal see, southwestern Sardinia, Italy. It lies west-northwest of Cagliari city. The town’s cathedral dates from 1288, and the 15th-century Church of San Francesco is a good example of Franciscan architecture in Sardinia. Iglesias is the centre of a region in which lead, zinc, and silver are mined and sulfuric acid is distilled. The local mining school house...
  • Iglesias, Pablo (Spanish politician)
    political leader who played a significant role in the development of Spanish democratic socialism and trade unionism....
  • Iglesias, Santiago (Puerto Rican politician)
    ...Party worked for greater autonomy. The Nationalist Party arose in the 1920s and argued for immediate independence. Meanwhile, the pro-U.S. Socialist Party, led by the highly respected labour leader Santiago Iglesias, remained focused on the plight of Puerto Rico’s labouring classes, but its program had little support, because popular attention was largely concentrated on the political st...
  • igloo (dwelling)
    temporary winter home or hunting-ground dwelling of Canadian and Greenland Inuit (Eskimos). The term igloo, or iglu, from Eskimo igdlu (“house”), is related to Iglulik, a town, and Iglulirmiut, an Inuit people, both on an island of the same name. The igloo, usually made from blocks of snow and dome-shaped, is used only in the area between the Mackenzie River...
  • iglu (dwelling)
    temporary winter home or hunting-ground dwelling of Canadian and Greenland Inuit (Eskimos). The term igloo, or iglu, from Eskimo igdlu (“house”), is related to Iglulik, a town, and Iglulirmiut, an Inuit people, both on an island of the same name. The igloo, usually made from blocks of snow and dome-shaped, is used only in the area between the Mackenzie River...
  • IgM (biochemistry)
    Antibodies are grouped into five classes according to their constant region. Each class is designated by a letter attached to an abbreviation of the word immunoglobulin: IgG, IgM, IgA, IgD, and IgE. The classes of antibody differ not only in their constant region but also in activity. For example, IgG, the most common antibody, is present mostly in the blood and tissue fluids,......
  • IGN (institution, France)
    one of the foremost centres of mapmaking and geographic research in France, specializing in aerial and ground surveys and maps; it is located in Paris. Its origins can be traced to a mapmaking group organized in 1719, the Engineers and Geographers for Armies and Camps, which produced several geodetic and triangulation maps of France. During the reign of Louis XV, the group made the first map of th...
  • Ignacio de Loyola, San (Spanish saint)
    Spanish theologian and one of the most influential figures in the Catholic Reformation of the 16th century, founder of the Society of Jesus (Jesuits) in Paris in 1534....
  • Ignacius (fossil primate genus)
    The first known supposed primates date to about 60 million years ago, as complete skulls and partial postcranial skeletons are available for the genera Plesiadapis, Ignacius, and Palaechthon from Europe and North America. The skulls show a number of dental specializations, including, in the case of Plesiadapis, procumbent rodentlike......
  • Ignarro, Louis J. (American scientist)
    American pharmacologist who, along with Robert F. Furchgott and Ferid Murad, was co-awarded the 1998 Nobel Prize in Physiology or Medicine for the discovery that nitric oxide (NO) acts as a signaling molecule in the cardiovascular system. This work uncovered an entirely new mechanism by which blood vessels...
  • Ignarro, Louis Joseph (American scientist)
    American pharmacologist who, along with Robert F. Furchgott and Ferid Murad, was co-awarded the 1998 Nobel Prize in Physiology or Medicine for the discovery that nitric oxide (NO) acts as a signaling molecule in the cardiovascular system. This work uncovered an entirely new mechanism by which blood vessels...
  • Ignatev, P. N., Count (Russian political leader)
    ...private initiative of the educationally minded intelligentsia, who were opposed to the authoritarian character of state education in the schools. In 1915–16 the minister of education, Count P.N. Ignatev, started serious reforms to modernize the secondary schools and to establish a system of vocational and technical education, which he regarded as most important for the industrialization....
  • Ignatiev, Nikolay Pavlovich, Graf (Russian statesman)
    pan-Slavist diplomat and statesman who played a major role in the administration of Russia’s foreign policy in Asia under Tsar Alexander II (reigned 1855–81)....
  • Ignatius of Antioch, Saint (Syrian bishop)
    bishop of Antioch, Syria, known mainly from seven highly regarded letters that he wrote during a trip to Rome, as a prisoner condemned to be executed for his beliefs. He was apparently eager to counteract the teachings of two groups—the Judaizers, who did not accept the authority of the New Testament, and the Docetists, who held that Christ’s sufferings and death were apparent but no...
  • Ignatius of Constantinople, Saint (patriarch of Constantinople)
    ...for their leaders among the monks of Studion, the monastery founded by Studius, and they found one in the person of the monastery’s abbot, St. Theodore Studites (759–826). In the patriarch Ignatius (847–858; 867–877) they discovered a spokesman after their own hearts: one drawn from the monastic ranks and contemptuous of all the allurements that the world of secular....
  • Ignatius of Loyola, Saint (Spanish saint)
    Spanish theologian and one of the most influential figures in the Catholic Reformation of the 16th century, founder of the Society of Jesus (Jesuits) in Paris in 1534....
  • Ignatius Theophoros (Syrian bishop)
    bishop of Antioch, Syria, known mainly from seven highly regarded letters that he wrote during a trip to Rome, as a prisoner condemned to be executed for his beliefs. He was apparently eager to counteract the teachings of two groups—the Judaizers, who did not accept the authority of the New Testament, and the Docetists, who held that Christ’s sufferings and death were apparent but no...
  • Ignatow, David (American poet)
    American poet whose works address social as well as personal issues in meditative, vernacular free verse....
  • Ignatyev, Nikolay Pavlovich, Graf (Russian statesman)
    pan-Slavist diplomat and statesman who played a major role in the administration of Russia’s foreign policy in Asia under Tsar Alexander II (reigned 1855–81)....
  • Ignatz Mouse (cartoon character)
    “Krazy Kat” was unique in a number of ways. The cast of characters was small and the basic plot always the same: Krazy Kat loved Ignatz Mouse, but the malicious Ignatz would have none of it and took every opportunity to throw a brick at Krazy. The policeman Offissa Pupp tried to protect Krazy, often by putting Ignatz in jail. The landscape backgrounds in the comic strip were stark......
  • igneous breccia (geology)
    ...inches) in size; although bombs are ejected in a molten state (becoming rounded upon solidification), blocks are erupted as solid angular or subangular fragments. Upon accumulation, blocks form breccia, which are solid angular fragments larger than 64 mm....
  • igneous petrology (geology)
    Igneous petrology is concerned with the identification, classification, origin, evolution, and processes of formation and crystallization of the igneous rocks. Most of the rocks available for study come from the Earth’s crust, but a few, such as eclogites, derive from the mantle. The scope of igneous petrology is very large because igneous rocks make up the bulk of the continental and ocean...
  • igneous rock (geology)
    any of various crystalline or glassy rocks formed by the cooling and solidification of molten earth material. Igneous rocks comprise one of the three principal classes of rocks, the others being metamorphic and sedimentary....
  • “Ignez de Castro” (work by Ferreira)
    ...and example. His verse epistles, inspired by the moral and aesthetic tenets of humanism, reveal his integrity as a critic of society as well as his clear and vigorous style. His tragedy Castro (written c. 1558) was one of the first in modern European literature. It takes as its subject the death of the Portuguese national heroine Inês de Castro, who was murdered by......
  • ignimbrite (rock)
    rock composed of compacted volcanic ejecta (see tuff)....
  • ignis fatuus (phenomenon)
    in meteorology, a mysterious light seen at night flickering over marshes; when approached, it advances, always out of reach. The phenomenon is also known as will-o’-the-wisp and ignis fatuus (Latin: “foolish fire”). In popular legend it is considered ominous and is often purported to be the soul of one who has been rejected by hell carrying its own hell coal on its wanderings...
  • ignitable waste (pollution)
    Reactive wastes are chemically unstable and react violently with air or water. They cause explosions or form toxic vapours. Ignitable wastes burn at relatively low temperatures and may cause an immediate fire hazard. Corrosive wastes include strong acidic or alkaline substances. They destroy solid material and living tissue upon contact, by chemical reaction....
  • ignition (combustion)
    Black powder is relatively insensitive to shock and friction and must be ignited by flame or heat. In the early days such devices as torches, glowing tinder, and heated iron rods were used to ignite the powder and, in most cases, a train of the powder was led to the main charge in order to give the firer time to get to a safe place....
  • ignition condition (physics)
    ...between the fusion energy heating the plasma and the energy-loss rate, which is the sum of 3nkT/τ and the bremsstrahlung. The condition satisfying this balance is called the ignition condition. An equation relates the product of density and energy confinement time, denoted nτ, to a function that depends only on the plasma temperature and the type of fus...
  • ignition module (engineering)
    ...spark plugs (known as coil-on-plug). The major components of these systems are a coil pack, an ignition module, a crankshaft reluctor ring, a magnetic sensor, and an electronic control module. The ignition module controls the primary circuit to the coils, turning them on and off. The reluctor ring is mounted on the crankshaft so that as the crankshaft rotates the magnetic sensor is triggered......
  • ignition system (engineering)
    in a gasoline engine, means employed for producing an electric spark to ignite the fuel–air mixture; the burning of this mixture in the cylinders produces the motive force....
  • ignition temperature (physics)
    ...steps that depend on the properties of the combustible substance. It is initiated by external factors such as heat, light, and sparks. The reaction sets in as the mixture of combustibles attains the ignition temperature, and several aspects of this step can be defined....
  • ignitron (electronics)
    electron tube functioning as a rectifier to convert alternating current (AC) to direct current (DC). Each conduction cycle is started by an external voltage applied to the igniter, a small electrode touching the tube’s cathode, which is a pool of mercury. Electrons released by t...
  • ignorance (law)
    In most countries the law recognizes that a person who acts in ignorance of the facts of his action should not be held criminally responsible. Thus, one who takes and carries away the goods of another person, believing them to be his own, does not commit larceny, for he lacks the intent to steal. Ignorance of the law, on the other hand, is generally held not to excuse the actor; it is no......
  • ignorance, theory of (philosophy)
    Scottish metaphysician distinguished for his theory of agnoiology, or theory of ignorance....
  • IGO
    ...having activities in several states, and whose members are held together by a formal agreement. The Union of International Associations, a coordinating body, differentiates between the more than 250 international governmental organizations (IGOs), which have been established by intergovernmental agreements and whose members are states, and the approximately 6,000 nongovernmental organizations.....
  • Igo mask (African arts)
    ...restricted to rhythmic strides and gestures; in contrast, the simple cloth costumes of ancestral Egungun Elewe of the Igbomina-Yoruba allow for a dance of acrobatic skill, and the light raffia Igo masks of the neighbouring Edo people enable them to lift their costumes above their heads in a dance of whirling turns....
  • Igogo (African dance)
    In some areas dances are designed to be performed during funeral rites, after burial ceremonies, and at anniversaries. Dances may be created for a specific purpose, as in the Igogo dance of the Owo-Yoruba, when young men use stamping movements to pack the earth of the grave into place. In Fulani communities in Cameroon, the corpse is placed in a sitting position in a prominent place, and solo......
  • Igor (Russian prince)
    grand prince of Kiev and presumably the son of Rurik, prince of Novgorod, who is considered the founder of the dynasty that ruled Kievan Rus and, later, Muscovy until 1598. Igor, successor to the great warrior and diplomat Oleg (reigned c. 879–912), assumed the throne of Kiev in 912....
  • Igor Svyatoslavich (Russian prince)
    prince of the Russian lands of Novgorod-Seversky (modern Novhorod-Siverskyy, Ukraine) after 1178 and of Chernigovsky (1198–1202; modern Chernihiv, Ukraine), who led an unsuccessful campaign against the Cumans (Polovtsy) in 1185....
  • Igorot (people)
    any of various ethnic groups in the mountains of northern Luzon, Philippines, all of whom keep, or have kept until recently, their traditional religion and way of life. Some live in the tropical forests of the foothills, but most live in rugged grassland and pine forest zones higher up. The Igorot numbered about 500,000 in the late 20th century. Their languages belong to the nor...
  • Igor’s Campaign, The Song of (Russian literature)
    masterpiece of Old Russian literature, an account of the unsuccessful campaign in 1185 of Prince Igor of Novgorod-Seversky against the Polovtsy (Kipchak, or Cumans). As in the great French epic The Song of Roland, Igor’s heroic pride draws him into a combat in which the odds are too great for him. Though defeated, Igor escapes his captors and returns to his people....
  • “Igor’s Host, The Lay of” (Russian literature)
    masterpiece of Old Russian literature, an account of the unsuccessful campaign in 1185 of Prince Igor of Novgorod-Seversky against the Polovtsy (Kipchak, or Cumans). As in the great French epic The Song of Roland, Igor’s heroic pride draws him into a combat in which the odds are too great for him. Though defeated, Igor escapes his captors and returns to his people....
  • Igreja, Mount (mountain, Brazil)
    Behind the seacoast a great escarpment rises like a mountain wall; Santa Catarina has little level ground. Its highest point is Mount Igreja, at 5,932 feet (1,808 m) in elevation, located in the southeastern part of the state. There are two principal river systems, one formed by the coastal rivers flowing eastward to the coast, the other flowing south to the Uruguay River, which forms part of......
  • “Igrok” (novel by Dostoyevsky)
    ...would allow him nine years to publish all of Dostoyevsky’s works for free. With less than a month remaining, Dostoyevsky hired a stenographer and dictated his novel Igrok (1866; The Gambler)—based on his relations with Suslova and the psychology of compulsive gambling—which he finished just on time. A few months later (1867) he married the stenogra...
  • IGU
    ...before the first meetings in London (1895) and the United States (1904), and thus the notion was perpetuated at least among some that geography was still a “European” discipline. The International Geographical Union (IGU) was founded in 1922....
  • Igu (dance)
    ...in the Dibāng Valley region is largely undeveloped. Most distances are traveled over simple tracks, though there are a few all-weather roads. Anini is the chief settlement in the region. The Igu, a somber dance performed by the Idu Mishmi priests, is closely associated with the region....
  • Iguaçu, Cataratas do (waterfall, Argentina-Brazil)
    series of cataracts on the Iguaçu River, 14 miles (23 km) above its confluence with the Alto (Upper) Paraná River, at the Argentina-Brazil border. The falls resemble an elongated horseshoe that extends for 1.7 miles (2.7 km)—nearly three times wider than Niagara Falls...
  • Iguaçu, Declaration of (economic agreement, Argentina-Brazil)
    ...the economies of Latin America through the Latin American Free Trade Association (1960) and its successor, the Latin American Integration Association (1980). In 1985 Argentina and Brazil signed the Declaration of Iguaçu, which created a bilateral commission to promote the integration of their economies; by the following year the two countries had negotiated several commercial agreements....
  • Iguaçu Falls (waterfall, Argentina-Brazil)
    series of cataracts on the Iguaçu River, 14 miles (23 km) above its confluence with the Alto (Upper) Paraná River, at the Argentina-Brazil border. The falls resemble an elongated horseshoe that extends for 1.7 miles (2.7 km)—nearly three times wider than Niagara Falls...
  • Iguaçu National Park (park, Brazil)
    ...the establishment of a national park at Iguaçu Falls. Following boundary rectifications between Brazil and Argentina, two separate national parks were established, one by each country—Iguaçu National Park (1939) in Brazil and Iguazú National Park (1934) in Argentina. Both parks were created to preserve the vegetation, wildlife, and scenic beauty associated with the.....
  • Iguaçu, Rio (river, Brazil)
    river flowing through Santa Catarina and Paraná states in southern Brazil. The Iguaçu is formed by headstreams rising in the Serra do Mar near Curitiba. It winds generally westward through the uplands for about 820 miles (1,320 km) before joining the Paraná River at the point where Argentina, Brazil, and Paraguay meet. It forms a small portion of the Brazilian-Argentine border...
  • Iguaçu River (river, Brazil)
    river flowing through Santa Catarina and Paraná states in southern Brazil. The Iguaçu is formed by headstreams rising in the Serra do Mar near Curitiba. It winds generally westward through the uplands for about 820 miles (1,320 km) before joining the Paraná River at the point where Argentina, Brazil, and Paraguay meet. It forms a small portion of the Brazilian-Argentine border...
  • Iguaçu, Saltos do (waterfall, Argentina-Brazil)
    series of cataracts on the Iguaçu River, 14 miles (23 km) above its confluence with the Alto (Upper) Paraná River, at the Argentina-Brazil border. The falls resemble an elongated horseshoe that extends for 1.7 miles (2.7 km)—nearly three times wider than Niagara Falls...
  • Iguala (Mexico)
    city, north-central Guerrero estado (state), south-central Mexico. It was settled in 1750 and was named in honour of Agustín de Iturbide’s Iguala Plan, proclaiming Mexico an independent monarchy (Feb. 24, 1821). Iguala lies along the Cocula River and is an important regional commerce and communications centre. Products from much of Guerrero, inc...
  • Iguala de la Independencia (Mexico)
    city, north-central Guerrero estado (state), south-central Mexico. It was settled in 1750 and was named in honour of Agustín de Iturbide’s Iguala Plan, proclaiming Mexico an independent monarchy (Feb. 24, 1821). Iguala lies along the Cocula River and is an important regional commerce and communications centre. Products from much of Guerrero, inc...
  • Iguala Plan (Mexican history)
    (Feb. 24, 1821), appeal issued by Agustín de Iturbide, a creole landowner and a former officer in the Spanish army who had assumed leadership of the Mexican independence movement in 1820. His plan called for an independent Mexico ruled by a European prince (or by a Mexican—i.e., Iturbide himself—if no European could be found), reten...
  • Iguala, Plan de (Mexican history)
    (Feb. 24, 1821), appeal issued by Agustín de Iturbide, a creole landowner and a former officer in the Spanish army who had assumed leadership of the Mexican independence movement in 1820. His plan called for an independent Mexico ruled by a European prince (or by a Mexican—i.e., Iturbide himself—if no European could be found), reten...
  • iguana (lizard genus)
    (Feb. 24, 1821), appeal issued by Agustín de Iturbide, a creole landowner and a former officer in the Spanish army who had assumed leadership of the Mexican independence movement in 1820. His plan called for an independent Mexico ruled by a European prince (or by a Mexican—i.e., Iturbide himself—if no European could be found), reten...
  • iguana (lizard grouping)
    any of eight genera and roughly 30 species of the larger members of the lizard family Iguanidae. The name iguana usually refers only to the members of the subfamily Iguaninae. The best-known species is the common, or green, iguana (Iguana iguana), which occurs from Mexico southward to Brazil. Males of this species reach a maximum length of over 2 metr...
  • Iguana iguana (lizard)
    ...snakes also depart after the eggs are lain; the egg chamber can be little more than a hollow as the lizard or snake crawls through leaf litter or soil, or it may be more elaborate. For example, the common, or green, iguana (I. iguana) digs a deep burrow with a combination of its fore- and hind limbs; this chamber is often so deep that the female is totally hidden from view. At the end of...
  • Iguania (reptile infraorder)
    ...only influenced the disposition of taxonomic units but had cascading effects on the ecology of lizards and led to the diversification of snakes. This first split produced the iguanians (infraorder Iguania) and the scleroglossans (infraorder Scleroglossa), two large groups within order Squamata that were fundamentally different from each other. The ancestors of all lizards possessed an ability.....
  • iguanid (lizard)
    any of about 700 species of lizards in more than 40 genera that constitute the family Iguanidae. Iguanids are found throughout the Americas from southern Canada to the tip of South America. The only exceptions are one genus (Brachylophus) in Fiji and other Pacific islands and two genera (Oplurus and Chalarodon) in Madagascar. The family includes the common iguana (Iguana...
  • Iguanidae (lizard)
    any of about 700 species of lizards in more than 40 genera that constitute the family Iguanidae. Iguanids are found throughout the Americas from southern Canada to the tip of South America. The only exceptions are one genus (Brachylophus) in Fiji and other Pacific islands and two genera (Oplurus and Chalarodon) in Madagascar. The family includes the common iguana (Iguana...
  • Iguanodon (dinosaur genus)
    large herbivorous dinosaurs found as fossils from the Late Jurassic and Early Cretaceous periods (159 million to 99 million years ago) in a wide area of Europe, North Africa, North America, Australia, and Asia; a few have been found from Late Cretaceous deposits of Europe and southern Africa....
  • iguanodont (dinosaur)
    The skulls of iguanodonts accommodated still larger jaw muscles, but the cheek teeth were less regular and compacted than in the primitive ornithopods and consequently did not occlude as uniformly. Both the premaxillaries and the predentary were toothless but probably were sheathed in horny beaks....
  • Iguanodontidae (dinosaur)
    The skulls of iguanodonts accommodated still larger jaw muscles, but the cheek teeth were less regular and compacted than in the primitive ornithopods and consequently did not occlude as uniformly. Both the premaxillaries and the predentary were toothless but probably were sheathed in horny beaks....
  • Iguassú Falls (waterfall, Argentina-Brazil)
    series of cataracts on the Iguaçu River, 14 miles (23 km) above its confluence with the Alto (Upper) Paraná River, at the Argentina-Brazil border. The falls resemble an elongated horseshoe that extends for 1.7 miles (2.7 km)—nearly three times wider than Niagara Falls...
  • Iguassú River (river, Brazil)
    river flowing through Santa Catarina and Paraná states in southern Brazil. The Iguaçu is formed by headstreams rising in the Serra do Mar near Curitiba. It winds generally westward through the uplands for about 820 miles (1,320 km) before joining the Paraná River at the point where Argentina, Brazil, and Paraguay meet. It forms a small portion of the Brazilian-Argentine border...
  • Iguazú, Cataratas del (waterfall, Argentina-Brazil)
    series of cataracts on the Iguaçu River, 14 miles (23 km) above its confluence with the Alto (Upper) Paraná River, at the Argentina-Brazil border. The falls resemble an elongated horseshoe that extends for 1.7 miles (2.7 km)—nearly three times wider than Niagara Falls...
  • Iguazú Falls (waterfall, Argentina-Brazil)
    series of cataracts on the Iguaçu River, 14 miles (23 km) above its confluence with the Alto (Upper) Paraná River, at the Argentina-Brazil border. The falls resemble an elongated horseshoe that extends for 1.7 miles (2.7 km)—nearly three times wider than Niagara Falls...
  • Iguazú National Park (park, Argentina)
    ...Falls. Following boundary rectifications between Brazil and Argentina, two separate national parks were established, one by each country—Iguaçu National Park (1939) in Brazil and Iguazú National Park (1934) in Argentina. Both parks were created to preserve the vegetation, wildlife, and scenic beauty associated with the falls. In 1984 the Argentine park was designated a......
  • Iguazú, Río (river, Brazil)
    river flowing through Santa Catarina and Paraná states in southern Brazil. The Iguaçu is formed by headstreams rising in the Serra do Mar near Curitiba. It winds generally westward through the uplands for about 820 miles (1,320 km) before joining the Paraná River at the point where Argentina, Brazil, and Paraguay meet. It forms a small portion of the Brazilian-Argentine border...
  • Igusa Magosaburō (Japanese artist)
    Japanese painter and printmaker of the ukiyo-e (“pictures of the floating world”) movement. ...
  • Iguvine Tables (bronze inscriptions)
    a set of seven inscribed bronze tables found in 1444 at Iguvium (modern Gubbio, Italy), an Umbrian town. The tables are written in the Umbrian language, four and part of a fifth using the Umbrian script, the rest Latin characters. The earliest appear to date from the 3rd or 2nd century bc, the latest from the early part of the 1st century bc. These t...
  • Iguvium (Italy)
    town, Umbria regione of central Italy, lying at the foot of Mount Ingino, just northeast of Perugia. Gubbio (medieval Eugubium) grew up on the ruins of Iguvium, an ancient Umbrian town that later became an ally of Rome and a Roman municipium; the Roman theatre is the chief relic of the ancient town. Although sacked by the Goths, it was mentioned as a bishopric in ...
  • IGY
    worldwide program of geophysical research that was conducted from July 1957 to December 1958. IGY was directed toward a systematic study of the Earth and its planetary environment. The IGY encompassed research in 11 fields of geophysics: aurora and airglow, cosmic rays, geomagnetism, glaciology, gravity, ionospheric physics, longitude and latitude determinations, meteorology, oceanography, seismol...
Skip this Advertisement

Link to this article and share the full text with the readers of your Web site or blog-post.

If you think a reference to this article on "" will enhance your Web site, blog-post, or any other web-content, then feel free to link to this article, and your readers will gain full access to the full article, even if they do not subscribe to our service.

You may want to use the HTML code fragment provided below.

copy link

We welcome your comments. Any revisions or updates suggested for this article will be reviewed by our editorial staff. Contact us here.

Regular users of Britannica may notice that this comments feature is less robust than in the past. This is only temporary, while we make the transition to a dramatically new and richer site. The functionality of the system will be restored soon.

The Britannica Store
A-Z Browse

Image preview