Columbia Encyclopedia

Search results

484 results found

cell, in biology

(Encyclopedia)CE5 Animal cell cell, in biology, the unit of structure and function of which all plants and animals are composed. The cell is the smallest unit in the living organism that is capable of integrati...

deafness

(Encyclopedia)deafness, partial or total lack of hearing. It may be present at birth (congenital) or may be acquired at any age thereafter. A person who cannot detect sound at an amplitude of 20 decibels in a frequ...

colloid

(Encyclopedia)colloid kŏlˈoid [key] [Gr.,=gluelike], a mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance. The mixture is also...

guilds

(Encyclopedia)guilds or gilds, economic and social associations of persons engaging in the same business or craft, typical of Western Europe in the Middle Ages. Membership was by profession or craft, and the primar...

X-ray astronomy

(Encyclopedia)X-ray astronomy, study of celestial objects by means of the X rays they emit, in the wavelength range from 0.01 to 10 nanometers. X-ray astronomy dates to 1949 with the discovery that the sun emits X ...

symphony

(Encyclopedia)symphony [Gr.,=sounding together], a sonata for orchestra. The Italian operatic overture, called sinfonia, was standardized by Alessandro Scarlatti at the end of the 17th cent. into three sections, th...

pressure

(Encyclopedia)pressure, in mechanics, ratio of the force acting on a surface to the area of the surface; it is thus distinct from the total force acting on a surface. A force can be applied to and sustained by a si...

observatory, orbiting

(Encyclopedia)observatory, orbiting, research satellite designed to study solar radiation, electromagnetic radiation from distant stars, the earth's atmosphere, or the like. Because the atmosphere and other aspects...

space exploration

(Encyclopedia)CE5 Moon mission assembly CE5 Stages in a moon mission shown counterclockwise from launching on the first day to splashdown on the ninth day. space exploration, the investigation of physical co...

Moscow, city, Russia

(Encyclopedia)Moscow mŏsˈkou, –kō [key], Rus. Moskva, city (1991 est. pop. 8,802,000), capital of Russia and of Moscow region and the administrative center of the Central federal district, W central European R...