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echo sounder

(Encyclopedia)echo sounder, an older instrumentation system for indirectly determining ocean floor depth. Echo sounding is based on the principle that water is an excellent medium for the transmission of sound wave...

juniper

(Encyclopedia)juniper, any tree or shrub of the genus Juniperus, aromatic evergreens of the family Cupressaceae (cypress family), widely distributed over the north temperate zone. Many are valuable as a source of l...

sunflower

(Encyclopedia)sunflower, any plant of the genus Helianthus of the family Asteraceae (aster family), annual or perennial herbs native to the New World and common throughout the United States. In cultivation, the flo...

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...

smart weapon

(Encyclopedia)smart weapon, missile or steerable bomb equipped with a laser, television, or satellite guidance system. Smart weapons, which use guidance systems that rely on external assistance, are distinguished f...

snapping turtle

(Encyclopedia)snapping turtle, large, aggressive New World freshwater turtle. The two snapping turtle species are the sole members of the family Chelydridae. Snapping turtles prefer quiet, muddy water. They spend m...

ytterbium

(Encyclopedia)ytterbium ĭtûrˈbēəm [key] [for Ytterby, a town in Sweden], metallic chemical element; symbol Yb; at. no. 70; at. wt. 173.054; m.p. 819℃; b.p. about 1,194℃; sp. gr. about 7.0; valence +2 or +3...

billiards

(Encyclopedia)billiards, any one of a number of games played with a tapered, leather-tipped stick called a cue and various numbers of balls on a rectangular, cloth-covered slate table with raised and cushioned edge...

boric acid

(Encyclopedia)boric acid, any one of the three chemical compounds, orthoboric (or boracic) acid, metaboric acid, and tetraboric (or pyroboric) acid; the term often refers simply to orthoboric acid. The acids may be...

modem

(Encyclopedia)modem [modulator/demodulator], an external device or internal electronic circuitry used to transmit and receive digital data over a communications line normally used for analog signals. A modem attach...