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arc, in electricity

(Encyclopedia)arc, in electricity, highly luminous and intensely hot discharge of electricity between two electrodes. The arc was discovered early in the 19th cent. by the English scientist Sir Humphry Davy, who so...

arc, in geometry

(Encyclopedia)arc, in geometry, a curved line or any part of it; in particular, a portion of the circumference of a circle. The length s of an arc of a circle of radius r and subtending a central angle of θ radian...

key, in mechanics

(Encyclopedia)key, in mechanics: see lock and key. ...

Mars, in astronomy

(Encyclopedia)Mars, in astronomy, 4th planet from the sun, with an orbit next in order beyond that of the earth. Mars has two natural satellites, discovered by Asaph Hall in 1877. The innermost of these, Phobos...

martin, in zoology

(Encyclopedia)martin: see swallow.

milo, in botany

(Encyclopedia)milo or milo maize: see sorghum. ...

Mimosa, in astronomy

(Encyclopedia)Mimosa or Beta Crucis bāˈtə kro͞oˈsĭs [key], bright star in the constellation Crux (Southern Cross); 1992 position R.A. 12h47.3m, Dec. −59°39′. It is sometimes called Becrux, from its Bayer...

mimosa, in botany

(Encyclopedia)mimosa mĭmōˈsə [key], any tree, shrub, or herb of the genus Mimosa of the family Leguminosae (pulse family), chiefly tropical plants. They usually have feathery foliage and rounded clusters of fra...

mine, in industry

(Encyclopedia)mine, in industry: see mining.

mine, in warfare

(Encyclopedia)mine, in warfare, term formerly applied to a system of tunnels dug under an army fortification and ending in a chamber where either explosives were placed to be detonated at a chosen moment or the sup...