Columbia Encyclopedia

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boil

(Encyclopedia)boil or furuncle fyo͝orˈŭngkəl [key], tender, painful inflammatory nodule in the skin, which becomes pustular but with a hard center (see abscess). It may be caused by any of various microbes, the...

borax

(Encyclopedia)borax or sodium tetraborate decahydrate sōˈdēəm tĕˌtrəbôrˈāt dĕkˌəhīˈdrāt [key], chemical compound, Na2B4O7·10H2O; sp. gr. 1.73; slightly soluble in cold water; very soluble in hot wa...

Columbia, U.S. space shuttle

(Encyclopedia)Columbia, U.S. space shuttle. On its 28th flight, on Feb. 1, 2003, after completing a 16-day scientific mission, the spacecraft disintegrated during reentry, killing its seven-person crew. About 16 mi...

San Salvador, city, El Salvador

(Encyclopedia)San Salvador sän sälväᵺōrˈ [key], city (1993 pop. 402,448), central El Salvador, capital and largest city of the country. It is the center of El Salvador's trade and communications. Beer, tobac...

bee fly

(Encyclopedia)bee fly, name for the small- to medium-sized flies of the family Bombyliidae, many of which resemble bees in appearance and behavior. This mimicry provides bee flies with some measure of protection ag...

resistance, in electricity

(Encyclopedia)resistance, property of an electric conductor by which it opposes a flow of electricity and dissipates electrical energy away from the circuit, usually as heat. Optimum resistance is provided by a con...

permafrost

(Encyclopedia)permafrost, permanently frozen soil, subsoil, or other deposit, characteristic of arctic and some subarctic regions; similar conditions are also found at very high altitudes in mountain ranges. In 196...

sweetener, artificial

(Encyclopedia)sweetener, artificial, substance used as a low-calorie sugar substitute. Saccharin, cyclamates, and aspartame have been the most commonly used artificial sweeteners. Saccharin, a coal-tar derivative t...

tempering

(Encyclopedia)tempering, process involving slow and moderate heating to increase the hardness and toughness of metals that have undergone previous heat treatment. Metals are usually hardened (see hardening) by bein...

calcium oxide

(Encyclopedia)calcium oxide, chemical compound, CaO, a colorless, cubic crystalline or white amorphous substance. It is also called lime, quicklime, or caustic lime, but commercial lime often contains impurities, e...