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space medicine

(Encyclopedia)space medicine, study of the medical and biological effects of space travel on living organisms. The principal aim is to discover how well and for how long humans can withstand the extreme conditions ...

agrarian reform

(Encyclopedia)agrarian reform, redistribution of the agricultural resources of a country. Traditionally, agrarian, or land, reform is confined to the redistribution of land; in a broader sense it includes related c...

petroleum

(Encyclopedia)petroleum, oily, flammable liquid that occurs naturally in deposits, usually beneath the surface of the earth; it is also called crude oil. It consists principally of a mixture of hydrocarbons, with t...

arteriosclerosis

(Encyclopedia)arteriosclerosis ärtĭrˌēōsklərōˈsis [key], general term for a condition characterized by thickening, hardening, and loss of elasticity of the walls of the blood vessels. These changes are freq...

root, in botany

(Encyclopedia)CE5 Longitudinal cross section of a root root, in botany, the descending axis of a plant, as contrasted with the stem, the ascending axis. In most plants the root is underground, but in epiphytes ...

Ferdinand II, Holy Roman emperor

(Encyclopedia)Ferdinand II, 1578–1637, Holy Roman emperor (1619–37), king of Bohemia (1617–37) and of Hungary (1618–37); successor of Holy Roman Emperor Matthias. Grandson of Ferdinand I, son of Archduke Ch...

Huron, indigenous people of North America

(Encyclopedia)Huron hyo͝orˈänˌ [key], confederation of four Native North American groups who spoke the Wyandot language, which belongs to the Iroquoian branch of the Hokan-Siouan linguistic stock (see Native Am...

drug poisoning

(Encyclopedia)drug poisoning, toxic effects caused by an administered drug. Worldwide more than 9 million natural and synthetic chemicals have been identified; fewer than 3000 cause more than 95% of acidental and d...

brown dwarf

(Encyclopedia)brown dwarf, in astronomy, celestial body that is larger than a planet but does not have sufficient mass to convert hydrogen into helium via nuclear fusion as stars do. Also called “failed stars,”...

Bulgarian literature

(Encyclopedia)Bulgarian literature. For early ecclesiastical writings, see Church Slavonic. Modern Bulgarian literature stems from the work of Father Paisi, who in 1762 began his history of the Slav Bulgarians. The...