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commerce, in economics

(Encyclopedia)commerce, traffic in goods, usually thought of as trade between states or nations. Engaged in by all peoples from the earliest times, it has been carried on in some areas and by some peoples more than...

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...

fish, in zoology

(Encyclopedia)CE5 Anatomy of a ray-finned fish fish, limbless aquatic vertebrate animal with fins and internal gills. Traditionally the living fish have been divided into three class: the primitive jawless fish...

triangle , in mathematics

(Encyclopedia)triangle, in mathematics, plane figure bounded by three straight lines, the sides, which intersect at three points called the vertices. Any one of the sides may be considered the base of the triangle....

index, in publishing

(Encyclopedia)index, of a book or periodical, a list, nearly always alphabetical, of the topics treated. This list is usually at the back of a book, and the table of contents is in the front. The index seeks to dir...

wave, in physics

(Encyclopedia)wave, in physics, the transfer of energy by the regular vibration, or oscillatory motion, either of some material medium or by the variation in magnitude of the field vectors of an electromagnetic fie...

conglomerate, in geology

(Encyclopedia)conglomerate, in geology, sedimentary rock composed largely of pebbles or other rounded particles whose diameter is larger than 2 mm (.08 in.). Essentially a cemented gravel, conglomerates are formed ...

locust, in botany

(Encyclopedia)locust, in botany, any species of the genus Robinia, deciduous trees or shrubs of the family Leguminosae (pulse family) native to the United States and Mexico. The locusts have pendent clusters of flo...

mesa, in geology

(Encyclopedia)mesa māˈsə [key] [Span.,=table], name given in the SW United States to a small, isolated tableland or a flat-topped hill. Two or more of the sides are steep and usually perpendicular and some have ...

turkey , in zoology

(Encyclopedia)turkey, common name for a large game and poultry bird related to the grouse and the pheasant. Its name derives from its “turk-turk” call. Turkeys are indigenous to the New World; American fossils ...