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mirage

(Encyclopedia)mirage mĭräzhˈ [key], atmospheric optical illusion in which an observer sees in the distance a nonexistent body of water or an image, sometimes distorted, of some object or of a complete scene. Exa...

narcotic

(Encyclopedia)narcotic, any of a number of substances that have a depressant effect on the nervous system. The chief narcotic drugs are opium, its constituents morphine and codeine, and the morphine derivative hero...

nonlinear dynamics

(Encyclopedia)nonlinear dynamics, study of systems governed by equations in which a small change in one variable can induce a large systematic change; the discipline is more popularly known as chaos (see chaos theo...

cartel

(Encyclopedia)cartel kärtĕlˈ [key], national or international organization of manufacturers or traders allied by agreement to fix prices, limit supply, divide markets, or to fix quotas for sales, manufacture, or...

Somme, Battles of the

(Encyclopedia)Somme, Battles of the, two engagements fought during World War I near the Somme River, N France. The first battle (July–Nov., 1916) was an Allied offensive. The British, commanded by Field Marshal S...

titanium

(Encyclopedia)titanium tītāˈnēəm, tĭ– [key] [from Titan], metallic chemical element; symbol Ti; at. no. 22; at. wt. 47.867; m.p. 1,675℃; b.p. 3,260℃; sp. gr. 4.54 at 20℃; valence +2, +3, or +4. Titani...

radiation sickness

(Encyclopedia)radiation sickness, harmful effect produced on body tissues by exposure to radioactive substances. The biological action of radiation is not fully understood, but it is believed that a disturbance in ...

Saint Lawrence Seaway

(Encyclopedia)Saint Lawrence Seaway, international waterway, 2,342 mi (3,769 km) long, consisting of a system of canals, dams, and locks in the St. Lawrence River and connecting channels between the Great Lakes; op...

Pietism

(Encyclopedia)Pietism pīˈətĭzəm [key], a movement in the Lutheran Church (see Lutheranism), most influential between the latter part of the 17th cent. and the middle of the 18th. It was an effort to stir the c...

spiritual

(Encyclopedia)spiritual, a religious folk song of American origin, particularly associated with African-American Protestants of the southern United States. The African-American spiritual, characterized by syncopati...