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amnesia
amnesia , [Gr.,=forgetfulness], condition characterized by loss of memory for long or short intervals of time. It may be caused by injury, shock, senility, severe illness, or mental disease. Some cases of amnesia involve the unconscious suppression of a painful experience and everything remindful ...
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day
day period of time for the earth to rotate once on its axis. The ordinary day, or solar day, is measured relative to the sun, being the time between successive passages of the sun over a stationary observer's celestial meridian . The length of a solar day varies during the course of a year, so f...
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hydrotherapy
hydrotherapy use of water in the treatment of illness or injury. Although the medicinal and hygienic value of water was recognized by the early Greeks, hydrotherapy attained its widest use in the 18th and 19th cent. through the practice of the British physician Sir John Floyer and an Austrian peasa...
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heliograph
heliograph [Gr.,=sun-writer], signaling device using flashes of sunlight. It has two mirrors that are used to reflect sunlight on a distant point and a shutter through which the sunlight passes so that messages may be transmitted in telegraphic code by means of long and short flashes. It was used i...
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vertebral column
vertebral column (backbone; spinal column; spine) A flexible bony column in vertebrates that extends down the long axis of the body and provides the main skeletal support. It also encloses and protects the spinal cord and provides attachment for the muscles of the back. The vertebral column consists...
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Licking
Licking river, c.320 mi (515 km) long, rising in E Ky. and flowing NW to the Ohio River opposite Cincinnati; the North and South Forks are its chief tributaries. The Licking was an important means of travel for Native Americans and pioneers and later a busy trade route. In 1780, at the river's mout...
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Mystic
Mystic 1 River, c.10 mi (16 km) long, rising in SE Conn. and flowing S past Old Mystic and Mystic villages to the Long Island Sound. Mystic Seaport, a maritime museum, is at its mouth. 2 River, c.7 mi (11 km) long, rising in Mystic Lakes, E Mass., and flowing SE, past Medford, into Boston Harbo...
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centipede
centipede common name for members of a single class, Chilopoda, of the phylum Arthropoda . Centipedes are the most familiar of the myriapodous arthropods, which consist of five groups of arthropods that had a separate origin from other arthropods. Centipedes are widely distributed in temperate and...
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Niger
Niger , great river of W Africa, c.2,600 mi (4,180 km) long, rising on the Fouta Djallon plateau, SW Guinea, and flowing NE through Guinea and into Mali. In central Mali the Niger forms its vast inland delta (c.30,000 sq mi/77,700 sq km), a maze of channels and shallow lakes. An irrigation project i...
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square
square closed plane figure bounded by four straight line segments of equal length and meeting at right angles. The points of intersection of the lines, or sides, are called vertices. The diagonals of a square are the two lines joining opposite vertices; they are of equal length and are the perpendi...
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