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rapid transit

(Encyclopedia)rapid transit, transportation system designed to allow passenger travel within or throughout an urban area, usually employing surface, elevated, or underground railway systems or some combination of t...

automobile industry

(Encyclopedia)automobile industry, the business of producing and selling self-powered vehicles, including passenger cars, trucks, farm equipment, and other commercial vehicles. By allowing consumers to commute long...

nitrogen cycle

(Encyclopedia)CE5 Nitrogen cycle nitrogen cycle, the continuous flow of nitrogen through the biosphere by the processes of nitrogen fixation, ammonification (decay), nitrification, and denitrification. Nitrogen...

Ohio, river, United States

(Encyclopedia)Ohio, river, 981 mi (1,579 km) long, formed by the confluence of the Allegheny and Monongahela rivers in SW Pa., at Pittsburgh; it flows northwest, then generally southwest to enter the Mississippi Ri...

satire

(Encyclopedia)satire, term applied to any work of literature or art whose objective is ridicule. It is more easily recognized than defined. From ancient times satirists have shared a common aim: to expose foolishne...

Danube

(Encyclopedia)Danube dănˈyo͞ob [key], Czech Dunaj, Ger. Donau, Hung. Duna, Rom. Dunarea, Serbo-Croatian and Bulg. Dunav, Ukr. Dunay, great river of central and SE Europe, c.1,770 mi (2,850 km) long, with a drain...

mass transit

(Encyclopedia)mass transit, public transportation systems designed to move large numbers of passengers. The history of mass transportation is intimately connected to industrialization, urbanization, and the sepa...

Tennessee Valley Authority

(Encyclopedia)Tennessee Valley Authority (TVA), independent U.S. government corporate agency, created in 1933 by act of Congress; it is responsible for the integrated development of the Tennessee River basin. The h...

Black Sea

(Encyclopedia)Black Sea, inland sea, c.159,600 sq mi (413,360 sq km), between SE Europe and Asia, connected with the Mediterranean Sea by the Bosporus, the Sea of Marmara, and the Dardanelles. It is c.750 mi (1,210...

ecology

(Encyclopedia)ecology, study of the relationships of organisms to their physical environment and to one another. The study of an individual organism or a single species is termed autecology; the study of groups of ...