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bedbug

(Encyclopedia)bedbug, any of the small, blood-sucking bugs of the family Cimicidae, which includes about 30 species distributed throughout the world. Bedbugs are flat-bodied, oval, reddish brown, and about 1⁄4 in...

silica

(Encyclopedia)silica or silicon dioxide, chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white. It occurs in sev...

plasma

(Encyclopedia)plasma, in physics, fully ionized gas of low density, containing approximately equal numbers of positive and negative ions (see electron and ion). It is electrically conductive and is affected by magn...

vibration

(Encyclopedia)vibration, in physics, commonly an oscillatory motion—a movement first in one direction and then back again in the opposite direction. It is exhibited, for example, by a swinging pendulum, by the pr...

nickel

(Encyclopedia)nickel, metallic chemical element; symbol Ni; at. no. 28; at. wt. 58.6934; m.p. about 1,453℃; b.p. about 2,732℃; sp. gr. 8.902 at 25℃; valence 0, +1, +2, +3, or +4. Nickel is a hard, malleable, ...

Precambrian

(Encyclopedia)Precambrian, name of a major division of geologic time (see Geologic Timescale, tablegeologic timescale, table), from c.5 billion to 570 million years ago. It is now usually divided into the Archean a...

copper, chemical element

(Encyclopedia)copper, metallic chemical element; symbol Cu [Lat. cuprum=copper]; at. no. 29; at. wt. 63.546; m.p. 1,083.4℃; b.p. 2,567℃; sp. gr. 8.96 at 20℃; valence +1 or +2. Copper and some of its alloys ha...

Economic and Social Council

(Encyclopedia)Economic and Social Council, constituent organ of the United Nations. It was established by the UN Charter and has 54 (18 before 1965) member nations elected for three-year terms (one third every year...

Hasidim

(Encyclopedia)Hasidim or Chassidim both: häsēˈdĭm, khä– [key] [Heb.,=the pious], term used by the rabbis to describe those Jews who maintained the highest standard of religious observance and moral action. T...

Judges

(Encyclopedia)Judges, book of the Bible, seventh book of the Old Testament in the order of the Authorized Version. It is the sequel of Joshua in the biblical history, telling of the Hebrews in the Promised Land fro...