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saturation
saturation of an organic compound, condition occurring when its molecules contain no double or triple bonds and thus cannot undergo addition reactions. For example, ethane (H 3 C-CH 3 ) is a saturated compound. A compound is called unsaturated if it can undergo addition reactions. In the unsaturate...
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covalent bond
covalent bond A type of chemical bond in which atoms are held together in a molecule by sharing one or more pairs of electrons in their outer shells. For example, in the water molecule (H2O) each hydrogen atom forms a covalent bond by sharing its only electron with one of the six electrons in the ou...
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alkene
alkene , any of a group of aliphatic hydrocarbons whose molecules contain one or more carbon-carbon double bonds (see chemical bond ). Alkenes with only one double bond have the general formula C n H 2n . In the International Union of Pure and Applied Chemistry (IUPAC) system of chemical nomenclatu...
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woodwind
woodwind. Name for wind instrs. orig. and usually made of wood, either blown directly by mouth (fl. and recorder) or by means of a reed (cl. and ob.). Saxs. are classified as woodwind. double woodwind, in descriptions of a composer's scoring for orch., means 2 players of each standard type of woodwi...
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double bass
double bass bowed stringed musical instrument, the contrabass of the modern orchestral string section. It originated as a double-bass viol , an instrument described as early as 1566. A true double-bass violin appeared during the 18th cent. but was rejected as unwieldy and of poor tonal quality. ...
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outrigger
outrigger canoe-type vessel with a wood or bamboo float attached to the side of the craft and extending out over the water. The term outrigger also refers to the float itself. The craft is used throughout the South Pacific, although its greatest development has probably come in Sri Lanka, where t...
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shawm
shawm , double-reed woodwind instrument used in Europe from the 13th through the 17th cent. The term denotes a family of instruments of different sizes. The shape and tone of the soprano shawm are comparable to those of the oboe , of which it is a precursor. The shawm was constructed from a single ...
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Martina Navratilova
Martina Navratilova , 1956-, Czech-American tennis player, b. Prague. After holding the Czech singles title (1972-74), she defected (1975) to the United States. Known for her aggressive serve-and-volley style, she won the women's singles at Wimbledon a record nine times (1978-79, 1982-87, 1990) and ...
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switch
switch electrical device having two states: on, or closed; and off, or open. Ideally a switch offers a zero impedance to a current when it is closed, and it offers infinite impedance when open. Mechanical switches, which operate by moving contacts together and apart, are often classified by the n...
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contrabassoon
contrabassoon large, deep-toned instrument of the oboe family, also called double bassoon. Its tube, over 16 ft (5 m) long, is doubled upon itself four times. It was first made by Hans Schreiber of Berlin in 1620. Handel, Haydn, and Beethoven used it for special effects, but it was characterized by...
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