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liquid

(Encyclopedia)liquid, one of the three commonly recognized states in which matter occurs, i.e., that state, as distinguished from solid and gas, in which a substance has a definite volume but no definite shape. T...

dam

(Encyclopedia)dam, barrier, commonly across a watercourse, to hold back water, often forming a reservoir or lake; dams are also sometimes used to control or contain rockslides, mudflows, and the like in regions whe...

El Niño–Southern Oscillation

(Encyclopedia)El Niño–Southern Oscillation (ENSO) ĕl nēnˈyō [key], large-scale climatic fluctuation of the tropical Pacific Ocean and the overlying atmosphere. The El Niño [Span.,=the child] is the South Am...

wood

(Encyclopedia)CE5 Wood A. Cross section of a woody stem B. Enlarged view, showing xylem, phloem, and cambium wood, botanically, the xylem tissue that forms the bulk of the stem of a woody plant. Xylem conducts ...

water supply

(Encyclopedia)water supply, process or activity by which water is provided for some use, e.g., to a home, factory, or business. The term may also refer to the supply of water provided in this way. In the United Sta...

neutron star

(Encyclopedia)neutron star, extremely small, extremely dense star, with as much as double the sun's mass but only a few miles in radius, in the final stage of stellar evolution. Astronomers Baade and Zwicky predict...

nitric oxide

(Encyclopedia)nitric oxide or nitrogen monoxide, a colorless gas formed by the combustion of nitrogen and oxygen as given by the reaction: energy + N2 + O2 → 2NO; m.p. −163.6℃; b.p. −151.8℃. Nitric oxide ...

nonmetal

(Encyclopedia)nonmetal, chemical element possessing certain properties by which it is distinguished from a metal. In general, this distinction is drawn on the basis that a nonmetal tends to accept electrons and for...

National Forest System

(Encyclopedia)National Forest System, federally owned reserves, c.191 million acres (77.4 million hectares), administered by the Forest Service of the U.S. Dept. of Agriculture. The system is made up of 155 nationa...

Ledru-Rollin, Alexandre Auguste

(Encyclopedia)Ledru-Rollin, Alexandre Auguste älĕksäNˈdrə ôgüstˈ lədrüˈ-rôlăNˈ [key], 1807–74, French politician. A lawyer, he first became known as a radical opponent to the accession (1830) of Lou...