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Central Intelligence Agency

(Encyclopedia)Central Intelligence Agency (CIA), independent executive bureau of the U.S. government established by the National Security Act of 1947, replacing the wartime Office of Strategic Services (1942–45),...

Thoreau, Henry David

(Encyclopedia)Thoreau, Henry David thôrˈō, thərōˈ [key], 1817–62, American author, naturalist, social activist, and philosopher, b. Concord, Mass., grad. Harvard, 1837. Thoreau is considered one of the most...

Lewis and Clark expedition

(Encyclopedia)Lewis and Clark expedition, 1803–6, U.S. expedition that explored the territory of the Louisiana Purchase and the country beyond as far as the Pacific Ocean. The men were gathered and in the winte...

vaccination

(Encyclopedia)vaccination, means of producing immunity against pathogens, such as viruses and bacteria, by the introduction of an killed or weakened microorganism, a harmless piece of a microorganism, or the like t...

Emerson, Ralph Waldo

(Encyclopedia)Emerson, Ralph Waldo ĕmˈərsən [key], 1803–82, American poet and essayist, b. Boston. Through his essays, poems, and lectures, the “Sage of Concord” established himself as a leading spokesman...

forestry

(Encyclopedia)forestry, the management of forest lands for wood, water, wildlife, forage, and recreation. Because the major economic importance of the forest lies in wood and wood products, forestry has been chiefl...

endangered species

(Encyclopedia)endangered species, any plant or animal species whose ability to survive and reproduce has been jeopardized by human activities. In 1999 the U.S. government, in accordance with the U.S. Endangered Spe...

Industrial Revolution

(Encyclopedia)Industrial Revolution, term usually applied to the social and economic changes that mark the transition from a stable agricultural and commercial society to a modern industrial society relying on comp...

Oman

(Encyclopedia)CE5 Oman ōmänˈ [key], officially Sultanate of Oman, independent sultanate (2015 est. pop. 3,287,000), c.82,000 sq mi (212,380 sq km), SE Arabian peninsula, on the Gulf of Oman and the Arabian Se...

American literature

(Encyclopedia)American literature, literature in English produced in what is now the United States of America. The years immediately after World War I brought a highly vocal rebellion against established socia...