Columbia Encyclopedia

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medal

(Encyclopedia)medal, a piece of metal, cast or struck, often coin-shaped. The obverse and reverse bear bas-relief and inscription. Commemorative medals are issued in memory of a notable person or event. Civil and m...

knitting

(Encyclopedia)knitting, construction of a fabric made of interlocking loops of yarn by means of needles. Knitting, allied in origin to weaving and to the netting and knotting of fishnets and snares, was apparently ...

complex ion

(Encyclopedia)complex ion, charged molecular aggregate (see ion), consisting of a metallic atom or ion to which is attached one or more electron-donating molecules. In some complex ions, such as sulfate, SO4−2, t...

concretion

(Encyclopedia)concretion, mass or nodule of mineral matter, usually oval or nearly spherical in shape, and occurring in sedimentary rock. It is formed by the accumulation of mineral matter in the pore spaces of the...

hornbook

(Encyclopedia)hornbook, primer of a kind in use from the 15th to the 18th cent. On one side of a sheet of parchment or paper the matter to be learned was written or printed; over the sheet, for its protection, a tr...

waterproof and water-repellent fabrics

(Encyclopedia)waterproof and water-repellent fabrics, materials treated with various substances so as to make them impervious to water. Permanent waterproofing is achieved by first coating fabrics with rubber or pl...

plane

(Encyclopedia)plane, in mathematics, flat surface of infinite extent but no thickness. An example of a plane, or more exactly of a bounded portion of a plane, is the surface forming one face, or side, of a cube. A ...

sandblast

(Encyclopedia)sandblast, stream of sand or other abrasive particles driven by a jet of compressed air or water or by centrifugal force against a surface to clean or abrade it. When centrifugal force is used, the ab...

viaduct

(Encyclopedia)viaduct vīˈədŭktˌ [key] [Lat.,=road conveyor], type of bridge for carrying a highway or railroad over a valley, over low ground, or over a road. It is commonly constructed in the form of several ...

cocker spaniel

(Encyclopedia)cocker spaniel, breed of small sporting dog developed from English cocker spaniels brought to the United States in the 1880s. It stands from 14 to 15 in. (35.6–38.1 cm) high at the shoulder and weig...