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mental retardation

(Encyclopedia)mental retardation, below average level of intellectual functioning, usually defined by an IQ of below 70 to 75, combined with limitations in the skills necessary for daily living. Daily living skills...

Oregon Trail

(Encyclopedia)Oregon Trail, overland emigrant route in the United States from the Missouri River to the Columbia River country (all of which was then called Oregon). The pioneers by wagon train did not, however, fo...

Mamluk

(Encyclopedia)Mamluk or Mameluke mămˈəlo͞ok [key] [Arab.,=slaves], a warrior caste dominant in Egypt and influential in the Middle East for over 700 years. Islamic rulers created this warrior caste by collectin...

Kepler's laws

(Encyclopedia)CE5 Schematic representation of Kepler's second law: The areas ABF and A′B′F′ are equal and are swept out in equal intervals of time by a planet orbiting around the sun (at F). Kepler's laws...

voice, sound produced by living beings

(Encyclopedia)voice, sound produced by living beings. The source of the sound in human speaking and singing is the vibration of the vocal cords, which are inside the larynx, and the production of the sounds is call...

human evolution

(Encyclopedia)human evolution, theory of the origins of the human species, Homo sapiens. Modern understanding of human origins is derived largely from the findings of paleontology, anthropology, and genetics, and i...

global warming

(Encyclopedia)global warming, the gradual increase of the temperature of the earth's lower atmosphere as a result of the increase in greenhouse gases since the Industrial Revolution. Global warming and its effects,...

Arctic, the

(Encyclopedia)CE5 Arctic, the northernmost area of the earth, centered on the North Pole. The arctic regions are not coextensive with the area enclosed by the Arctic Circle (lat. 66°30′N) but are usually defi...

diplomatic service

(Encyclopedia)diplomatic service, organized body of agents maintained by governments to communicate with one another. In the 20th and 21st cent. there have been numerous meetings of heads of state and foreign min...

Herod

(Encyclopedia)Herod, dynasty reigning in Palestine at the time of Jesus. As a dynasty the Herods depended largely on the power of Rome. They are usually blamed for the state of virtual anarchy in Palestine at the b...