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family, in sociology

(Encyclopedia)family, a basic unit of social structure, the exact definition of which can vary greatly from time to time and from culture to culture. How a society defines family as a primary group, and the functio...

farming, in taxation

(Encyclopedia)farming, in the history of taxation, collection of taxes through private contractors. Usually, the tax farmer paid a lump sum to the public treasury; the difference between that sum and the sum actual...

fatigue, in engineering

(Encyclopedia)fatigue, in engineering, microscopic cracking of materials, especially metals, after repeated applications of stress. Fissures may be formed within pieces of metal during their manufacture when, while...

fatigue, in physiology

(Encyclopedia)fatigue, in physiology, inability to perform reasonable and necessary physical or mental activity. Muscle fatigue, for example, results when the contractile properties of muscle are reduced, and conti...

fox, in zoology

(Encyclopedia)fox, carnivorous mammal of the dog family, found throughout most of the Northern Hemisphere. It has a pointed face, short legs, long, thick fur, and a tail about one half to two thirds as long as the ...

Islam in Africa

(Encyclopedia)Islam in Africa, the development of the Muslim religion on the African continent. During Muhammad's lifetime a group of Muslims escaped Meccan persecution (615) by fleeing to Ethiopia, where the Negus...

ion, in chemistry

(Encyclopedia)ion, atom or group of atoms having a net electric charge. Ionization has many applications. Vapor lamps and fluorescent lamps take advantage of the light given off when positive ions recombine with ...

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