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numeral

(Encyclopedia)numeral, symbol denoting anumber. The symbol is a member of a family of marks, such as letters, figures, or words, which alone or in a group represent the members of a numeration system. The earliest ...

Mercator, Gerardus

(Encyclopedia)Mercator, Gerardus gārˈhärt krāˈmər [key], 1512–94, Flemish geographer, mathematician, and cartographer. He studied in Louvain, where he had a geographical establishment (1534). From 1537 to 1...

marsh antelope

(Encyclopedia)marsh antelope, name for members of a group of deerlike African antelopes, usually found in reeds or tall grasses near water. The males of this group have horns that curve back, up, and forward; femal...

thunderstorm

(Encyclopedia)thunderstorm, violent, local atmospheric disturbance accompanied by lightning, thunder, and heavy rain, often by strong gusts of wind, and sometimes by hail. The typical thunderstorm caused by convect...

bonobo

(Encyclopedia)bonobo, smaller of two species of chimpanzee, genus Pan. Whereas the common chimpanzee, P. troglodytes, lives in forests across most of equatorial Africa, the bonobo, P. paniscus (sometimes called the...

navigation satellite

(Encyclopedia)navigation satellite, artificial satellite designed expressly to aid the navigation of sea and air traffic. Early navigation satellites, from the Transit series launched in 1960 to the U.S. navy's Nav...

distortion

(Encyclopedia)distortion, in electronics, undesired change in an electric signal waveform as it passes from the input to the output of some system or device. In an audio system, distortion results in poor reproduct...

Tesla, Nikola

(Encyclopedia)Tesla, Nikola tĕsˈlə [key], 1856–1943, American electrician and inventor, b. Croatia (then an Austrian province). An ethnic Serb, he immigrated to the United States in 1884, worked for a short pe...

Goldmark, Peter Carl

(Encyclopedia)Goldmark, Peter Carl, 1906–77, Hungarian-American engineer, b. Budapest. He studied at the Univ. of Vienna (B.S., 1929, Ph.D., 1931); worked for a radio company in England (1931–33). After emigrat...

neurology

(Encyclopedia)neurology no͝orŏlˈəjē, nyo͝o– [key], study of the morphology, physiology, and pathology of the human nervous system. As researchers, neurologists carry on investigative and experimental work i...