English Denis The Little celebrated 6th-century canonist who is considered the inventor of the Christian calendar, the use of which spread through the employment of his new Easter tables.
Greek historian and teacher of rhetoric whose history of Rome, from its origins to the First Punic War, written from a pro-Roman standpoint but carefully researched, is, with Livy's, the ...
patriarch of the Syrian Jacobite church and author of an important source document on Eastern Christianity between the reigns of the Byzantine emperors Mauricius (582-602) and Theophilus (829-842).
biblical figure, converted by St. Paul at Athens (Acts 17:34), who acquired a notable posthumous reputation primarily through confusion with later Christians similarly named. In the 2nd century he was ...
Flemish Denys Van Leeuwen, or De Leeuwis, also called Denys Ryckel, or Van Rijkel theologian and mystic, one of the important contributors to, and propagators of, the influential school of ...
tyrant of Syracuse from 405 who, by his conquests in Sicily and southern Italy, made Syracuse the most powerful Greek city west of mainland Greece. Although he saved Greek Sicily ...
in Greco-Roman religion, a nature god of fruitfulness and vegetation, especially known as a god of wine and ecstasy. Though introduced from Thrace and Phrygia, the strange legends of his ...
prototype of Greek theatres, situated on the south side of the Acropolis in Athens, in which all extant classical Greek plays were first presented. Development on the site began with ...
a New World genus of ornamental cycads (plants of the family Cycadaceae). It is the most primitive American genus in the family and includes four or more species. The spiny-leaved, ...
equation involving only sums, products, and powers in which all the constants are integers and the only solutions of interest are integers. For example, 3x + 7y = 1 or x2 − y2 = z3, where x, y, ...
common silicate mineral in the pyroxene family that occurs in metamorphosed siliceous limestones and dolomites and in skarns (contact-metamorphic rocks rich in iron); it is also found in small amounts ...
in optics, unit of magnifying power of a lens or lens system. Because the power of a lens is proportional to unity (one) divided by the focal length (see lens), ...
three-dimensional exhibit, frequently housed in a cubicle and viewed through an aperture. It usually consists of a flat or curved back cloth on which a scenic painting or photograph is ...
medium- to coarse-grained intrusive igneous rock that commonly is composed of about two-thirds plagioclase feldspar and one-third dark-coloured minerals, such as hornblende or biotite. The presence of sodium-rich feldspar, oligoclase ...
the yam family of the flowering plant order Liliales, consisting of 6 genera with more than 500 species of herbaceous or woody vines and shrubs, distributed throughout tropical and warm ...
Greek physician and pharmacologist whose work De materia medica was the foremost classical source of modern botanical terminology and the leading pharmacological text for 16 centuries.
patriarch of Alexandria and Eastern prelate whose subscription to the unorthodox beliefs of the Monophysites caused him to be deposed and excommunicated by the Council of Chalcedon in 451. He ...
in Greek and Roman mythology, twin deities who succoured shipwrecked sailors and received sacrifices for favourable winds. They were the children of Leda and either Zeus, the king of the ...
genus of over 400 species of trees and shrubs of the ebony family (Ebenaceae), either deciduous or evergreen, most of which are native to the tropics. The usually alternate leaves ...
town, western Senegal, about 90 miles (145 km) east of Dakar. The market for a peanut- (groundnut-) growing area, Diourbel produces peanut oil as well as beverages and perfume. The ...
any of a group of chemical compounds that is an undesirable by-product in the manufacture of herbicides, disinfectants, and other agents. In popular terminology, dioxin has become a synonym for ...
(Pali: "History of the Island"), oldest extant historical record of Sri Lanka, compiled in the 4th century. It is considered to be one of the main sources drawn upon by ...
synthetic drug used in the treatment of various conditions including hay fever, acute skin reactions (such as hives), contact dermatitis (such as from poison ivy), and motion sickness. Diphenhydramine counteracts ...
in chemical warfare, poison gas widely used by Germany during World War I. Its chemical name is trichloromethyl chloroformate, and it is a colourless, moderately persistent, poisonous, organic compound, the ...
acute infectious disease caused by the bacillus Corynebacterium diphtheriae and characterized by a primary lesion, usually in the upper respiratory tract, and more generalized symptoms resulting from the spread of ...
in phonetics, a gliding vowel in the articulation of which there is a continuous transition from one position to another. Diphthongs are to be contrasted in this respect with so-called ...
gigantic dinosaurs found in North America as fossils from the Late Jurassic Period (159 million to 144 million years ago). Diplodocus is perhaps the most commonly displayed dinosaur. It, along ...
genus of graptolites, small, extinct colonial marine animals thought to be related to the primitive chordates and restricted to ancient marine environments. Forms or species of Diplograptus are useful index, ...
the established method of influencing the decisions and behaviour of foreign governments and peoples through dialogue, negotiation, and other measures short of war or violence. Modern diplomatic practices are a ...
in international law, the immunities enjoyed by foreign states or international organizations and their official representatives from the jurisdiction of the country in which they are present.
the study of documents. The term is derived from the Greek word diploma, meaning "doubled" or "folded." Besides the documents of legal and administrative import withwhich it is properly concerned, ...
any member of the protozoan order Diplomonadida. Diplomonads are small zooflagellates that inhabit the digestive systems of various animals, including termites, rats, and humans. They typically have two nuclei, each ...
genus of extinct amphibians of North America and Europe known from fossils in Late Carboniferous rocks (from 320 to 286 million years ago). Diplovertebron represents a late surviving form of ...
group of small primitive wingless insects (about 400 species) of the subclass Apterygota. Some entomologists consider many of their features similar to those associated with ancestral insects. Diplurans are blind, ...
Javanese leader in the 19th-century conflict known to the West as the Java War and to Indonesians as Dipo Negoro's War (1825-30). During those five years Dipo Negoro's military accomplishments ...
in classical prosody, a pair of metrical feet that is taken as a single unit. Trochaic, iambic, and anapestic verse are all measured by dipodies. In them a monometer consists ...
theory that the Earth's magnetic field is produced or is best represented by a magnetic dipole, a body having poles of opposite sign, that is, positive and negative. In the ...
city, western Mindanao, Philippines. Dipolog is a fishing and interisland shipping port. There is also a commercial airport. Its city status dates from 1969; it had been a municipality since ...
any of four species of songbirds of the Cinclidae family (order Passeriformes) noted for insect hunting by walking underwater in rushing streams and named for their frequent body bobbing.
family of extinct marsupial mammals that existed from the Late Oligocene epoch into the Pleistocene epoch (from 30 million to roughly 10,000 years ago) in Australia. It included Diprotodon, which ...
the teasel order of flowering plants, belonging to the class known as dicotyledon (q.v.; characterized by two seed leaves). It comprises 40 genera and about 1,100 species in four families ...
a serpent with a bite said to produce intense thirst. The snake was the subject of a story told by several Greek authors, including Sophocles. According to the legend, Zeus ...
a member of the insect order Diptera, the two-winged or "true" flies. This order contains over 85,000 species divided into three suborders: the Nematocera (midges, gnats, mosquitoes, crane flies), the ...
any member of the insect order Diptera, the two-winged or so-called true flies. Although many winged insects are commonly called flies, the name is strictly applicable only to members of ...
family of South Asian and African timber trees, in the tea order (Theales), comprising 22 genera. Most of the species are lofty trees with leathery, evergreen leaves and aromatic resins. ...
genus of very primitive lungfish, among the earliest known, found as fossils in European and North American Devonian rocks (the Devonian Period lasted from 408 to 360 million years ago). ...
town and district of Malakand division, North-West Frontier Province, Pakistan. The town, the district headquarters, lies just north of the Dir River, an affluent of the Panjkora, and is connected ...
(1818), major defeat dealt the Wahhabis, fanatical and puritanical Muslim reformers of Najd, central Arabia, by the forces of the Egyptian ruler Muhammad 'Ali Pasha; the Wahhabi empire was destroyed, ...
English theoretical physicist who was one of the founders of quantum mechanics and quantum electrodynamics. Dirac is most famous for his 1928 relativistic quantum theory of the electron and his ...
town, east-central Ethiopia, located on the eastern edge of the East African Rift Valley, 30 miles (48 km) northwest of Harer. It lies at the intersection of roads from Addis ...
British rock band whose supple, slightly blues-tinged guitar rock was popular in the late 1970s and '80s. The original members were Mark Knopfler (b. Aug. 12, 1949, Glasgow, Scot., ), ...
(species Canis dirus), wolf that existed during the Pleistocene Epoch (1,600,000 to 10,000 years ago). It is probably the most common mammalian species to be found preserved in the La ...
French clandestine terrorist group that emerged in 1979 and is believed to have been an amalgam of earlier extremist groups. Sometimes compared with older terrorist groups such as the Italian ...
flow of electric charge that does not change direction. Direct current is produced by batteries, fuel cells, rectifiers, and generators with commutators. Direct current was supplanted by alternating current (AC) ...
any of a class of coloured, water-soluble compounds that have an affinity for fibre and are taken up directly, such as the benzidine derivatives. Direct dyes are usually cheap and ...
the craft of controlling the evolution of a performance out of material composed or assembled by an author. The performance may be live, as in a theatre and in some ...
way of graphically representing the solutions of a first-order differential equation without actually solving the equation. The equation y' = f (x,y) gives a direction, y', associated with each point ...
radio receiver and antenna system for determining the direction of the source of a radio signal. A direction finder (DF) can be used by an aircraft or ship as a ...
style of dress, furniture, and ornament popular in France during the period of the Directory (1795-99). Dress for men, mixing ancient and contemporary elements, featured trousers and high boots, vests, ...
city, southwestern Nicaragua. It lies in the Diriamba Highlands at an elevation of 1,891 feet (576 m). Diriamba is a major commercial and manufacturing centre; its hinterland is known primarily ...
in mathematics, the problem of formulating and solving certain partial differential equations that arise in studies of the flow of heat, electricity, and fluids. Initially, the problem was that of ...
statement that there are infinitely many prime numbers contained in the collection of all numbers of the form na + b, in which the constants a and b are integers ...
German mathematician who made valuable contributions to number theory, analysis, and mechanics. He taught at the universities of Breslau (1827) and Berlin (1828-55) and in 1855 succeeded Carl Friedrich Gauss ...
