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exobiology

(Encyclopedia)exobiology or astrobiology, search for extraterrestrial life within the solar system and throughout the universe. Philosophical speculation that there might be other worlds similar to ours dates back ...

piano

(Encyclopedia)piano or pianoforte, musical instrument whose sound is produced by vibrating strings struck by felt hammers that are controlled from a keyboard. The piano's earliest predecessor was the dulcimer. The ...

Niagara Falls, waterfall, United States and Canada

(Encyclopedia)Niagara Falls, in the Niagara River, W N.Y. and S Ont., Canada; one of the most famous spectacles in North America. The falls are on the international line between the cities of Niagara Falls, N.Y., a...

bell, musical instrument

(Encyclopedia)CE5 Bell bell, in music, a percussion instrument consisting of a hollow metal vessel, often cup-shaped with an outward-flaring rim, damped at one end and set into vibration by a blow from a clappe...

zirconium

(Encyclopedia)zirconium zərkōˈnēəm [key], metallic chemical element; symbol Zr; at. no. 40; at. wt. 91.224; m.p. about 1,852℃; b.p. 4,377℃; sp. gr. 6.5 at 20℃; valence +2, +3, or +4. Zirconium is a very ...

Charleston, cities, United States

(Encyclopedia)Charleston. 1 City (2020 pop. 17,286), seat of Coles co., E Ill.; inc. 1835. Charleston is an industrial, rail, and trade center located in an ...

tunnel

(Encyclopedia)tunnel, underground passage usually made without removing the overlying rock or soil. Although tunnels are approximately horizontal, they must be built with sufficient gradient for proper drainage. Tu...

lever

(Encyclopedia)CE5 Classes of levers: A first-class lever (A), a second-class lever (B), and a third-class lever (C) lever, simple machine consisting of a bar supported at some stationary point along its length ...

Dylan, Bob

(Encyclopedia)Dylan, Bob dĭlˈən [key], 1941–, American singer and composer, b. Duluth, Minn., as Robert Zimmerman. Dylan learned guitar at the age of 10 and autoharp and harmonica at 15. After a rebellious you...

competition, in economics

(Encyclopedia)competition, in economics, rivalry in supplying or acquiring an economic service or good. Sellers compete with other sellers, and buyers with other buyers. In its perfect form, there is competition am...