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(Encyclopedia)labor, term used both for the effort of performing a task and for the workers engaged in the activity. In ancient times much of the work was done by slaves (see slavery). In the feudal period agricult...

Ariel, in astronomy

(Encyclopedia)Ariel ârˈēəl [key], in astronomy, one of the moons, or natural satellites, of Uranus. ...

lake, in dyeing

(Encyclopedia)lake, in dyeing, an insoluble pigment formed by the reaction between an organic dye and a mordant. The color of a lake depends upon the mordant as well as the dye used. Generally, lakes are not as col...

pitch, in aviation

(Encyclopedia)pitch, in aviation: see airplane; airfoil. ...

Pleiades, in astronomy

(Encyclopedia)Pleiades plēˈədēz, plīˈ– [key], in astronomy, famous open star cluster in the constellation Taurus; cataloged as M45. The cluster consists of some 500 stars, has a diameter of 35 light-years, ...

plum, in botany

(Encyclopedia)plum, common name for a tree of any of many species of the genus Prunus of the family Rosaceae (rose family) and for its fruit, a drupe. The plum is generally cultivated in the temperate zones, though...

Pluto, in astronomy

(Encyclopedia)Pluto, in astronomy, a dwarf planet and the first Kuiper belt, or transneptunian, object (see comet) to be discovered (1930) by astronomers. Pluto has an elliptical orbit usually lying beyond that of ...

pod, in aviation

(Encyclopedia)pod, in aviation: see airplane.

pod, in botany

(Encyclopedia)pod or legume, dehiscent fruit of a member of the family Leguminosae (pulse family). At maturity the pod splits along its two seams and releases the enclosed seeds. ...