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meteor

(Encyclopedia)meteor, appearance of a small particle flying through space that interacts with the earth's upper atmosphere. While still outside the atmosphere, the particle is known as a meteoroid. Countless meteor...

testosterone

(Encyclopedia)CE5 testosterone tĕstŏsˈtərōn [key], principal androgen, or male sex hormone. One of the group of compounds known as anabolic steroids, testosterone is secreted by the testes (see testis) but ...

beech

(Encyclopedia)CE5 American beech Fagus grandifolia beech, common name for the Fagaceae, a family of trees and shrubs mainly of temperate and subtropical regions in the Northern Hemisphere. The principal genera�...

tracery

(Encyclopedia)CE5 Types of tracery tracery, bands or bars of stone, wood, or other material, either subdividing an opening or standing in relief against a wall and forming an ornamental pattern of solid members...

seasons

(Encyclopedia)CE5 The seasons are caused by the tilt of the earth's axis to the plane of its orbit about the sun. The Northern Hemisphere is tilted toward the sun in the summer and receives more direct rays than...

barometer

(Encyclopedia)CE5 Aneroid barometer barometer bərŏmˈətər [key], instrument for measuring atmospheric pressure. It was invented in 1643 by the Italian scientist Evangelista Torricelli, who used a column...

alkane

(Encyclopedia)CE5 Alkanes alkane ălˈkān [key], any of a group of aliphatic hydrocarbons whose molecules contain only single bonds (see chemical bond). Alkanes have the general chemical formula CnH2n+2. An al...

feathers

(Encyclopedia)CE5 Structure of a bird feather feathers, outgrowths of the skin, constituting the plumage of birds. Feathers grow only along certain definite tracts (pterylae), which vary in different groups of ...

gastropod

(Encyclopedia)CE5 Internal anatomy of a snail, Helix aspersa, representative mollusk of the class Gastropoda gastropod, member of the class Gastropoda, the largest and most successful class of mollusks (phylum ...

heating

(Encyclopedia)CE5 Typical warm-air heating system heating, means of making a building comfortably warm relative to a colder outside temperature. Old, primitive methods of heating a building or a room within it ...