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complementarity principle

(Encyclopedia)complementarity principle, physical principle enunciated by Niels Bohr in 1928 stating that certain physical concepts are complementary. If two concepts are complementary, an experiment that clearly i...

Constitutions, Apostolic

(Encyclopedia)Constitutions, Apostolic, late-4th-century compilation, in eight books, of administrative canons for the clergy and the laity and of guides for worship. They were supposed to be works of the apostles,...

convulsion

(Encyclopedia)convulsion, sudden, violent, involuntary contraction of the muscles of the body, often accompanied by loss of consciousness. It is not known what causes the abnormal impulses from the brain that resul...

Cushman, Charlotte Saunders

(Encyclopedia)Cushman, Charlotte Saunders ko͝oshˈmən [key], 1816–76, one of the first outstanding American actresses, b. Boston. Cushman turned from opera to drama and in 1835 first played Lady Macbeth, the ro...

dispersion, in chemistry

(Encyclopedia)dispersion, in chemistry, mixture in which fine particles of one substance are scattered throughout another substance. A dispersion is classed as a suspension, colloid, or solution. Generally, the par...

field spaniel

(Encyclopedia)field spaniel, breed of medium-sized sporting dog developed in England from crosses between cocker spaniels and Sussex spaniels. It stands about 18 in. (45.7 cm) high at the shoulder and weighs about ...

unicorn

(Encyclopedia)unicorn yo͞oˈnĭkôrn [key], fabulous equine beast with a long horn jutting from the middle of its forehead. Once thought to be native to India, the unicorn was reportedly seen throughout the world....

Priapulida

(Encyclopedia)Priapulida, phylum consisting of 17 species of predatory, unsegmented marine worms that live in the sand and mud at the sea bottom. The largest are 4 to 6 in. (10–17 cm) long, but the majority of sp...

Pyrrho

(Encyclopedia)Pyrrho pĭrˈō [key], c.360–270 b.c., Greek philosopher, a native of Elis, regarded as the father of skepticism. After accompanying Alexander the Great to Asia, he enjoyed great respect at Elis and...

Gagarin, Yuri Alekseyevich

(Encyclopedia)Gagarin, Yuri Alekseyevich yo͞oˈrē əlyĭksyāˈyəvĭch gägäˈrĭn [key], 1934–68, Russian astronaut (cosmonaut), b. near Gzhatsk, RSFSR. He was the first in history to be rocketed into orbita...