: A South American herb, formally known as Nicotiana tabacum, whose leaves contain 2-8% nicotine and serve as the source of smoking and smokeless tobacco. Nicotiana tabacum presents a huge health problem. Disease and premature death continue to be caused by the use of tobacco. About 50 million Americans smoked in the year 2000. Of those who quit, 90% do so on their own. But in a given year, only about 1.7 million American smokers (3.6%) stop smoking.
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A South American herb, Nicotiana tabacum, that has large ovate to lanceolate leaves and terminal clusters of tubular white or pink flowers. T. leaves contain 2–8% of nicotine and are the source of smoking and chewing t.. T. smoke contains nicotine, carbon monoxide (4%), nitric oxide, and numerous aromatic hydrocarbons and other substances known to be carcinogens, including benzo[a]pyrene, β-naphthylamine, and nitrosamines.Cigarette smoking is the leading preventable cause of disease and death in the U.S., being responsible for approximately 434,000 deaths (20% of all deaths) each year. Smoking 2 packages of cigarettes a day reduces life span by 8.3 years. Smoking t. in any form (cigarettes, cigars, pipe) is a strong independent risk factor for atherosclerosis, acute myocardial infarction, unstable angina, stroke, and sudden death. It is responsible for 45% of all deaths due to coronary artery disease in men under 65 and more than 50% of all strokes in both sexes before age 65. Smoking lowers HDL cholesterol and raises LDL and VLDL cholesterol, and increases the risk of intermittent claudication and aortic aneurysm. It may cause as much as a 30-fold increase in the risk of thromboembolic disease in women taking oral contraceptives. Smoking is responsible for 100,000 deaths each year due to lung cancer, and markedly increases the risk of other cancers, particularly those of the oral cavity, larynx, esophagus, kidney, bladder, uterine cervix, and pancreas. Cigarette smoking is the principal cause of chronic bronchitis and emphysema. Passive smoking (inhalation by nonsmokers of second-hand or sidestream smoke) causes 53,000 deaths annually, 37,000 of them due to coronary artery disease. Maternal smoking during pregnancy is associated with increased risk of miscarriage, stillbirth, and low birth weight. Children of smokers are at increased risk of sudden infant death syndrome and meningococcal meningitis. Use of smokeless t. (chewing t., snuff) greatly increases the risk of cancer and premalignant lesions of the oral cavity. Nicotine use is powerfully addictive, leading to habituation, tolerance, and dependency. In the U.S., 90% of smokers become habituated to t. before age 21; 3000 children begin smoking each day. The likelihood of becoming and remaining a smoker increases in inverse proportion to the number of years of education completed. Quitting smoking decreases the risk of death from all causes by 30%. Effective strategies for smoking cessation include behavior modification therapy, nicotine replacement (gum, skin patches, inhaler), hypnosis, and drug therapy (bupropion), but the relapse rate 3 months after smoking cessation is 60%.
- wild t. SYN: lobelia.

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to·bac·co tə-'bak-(.)ō n, pl -cos
1) any plant of the genus Nicotiana esp an annual So. American herb (N. tabacum) cultivated for its leaves
2) the leaves of cultivated tobacco prepared for use in smoking or chewing or as snuff
3) manufactured products of tobacco also the use of tobacco as a practice

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the dried leaves of the plant Nicotiana tabacum or related species, used in smoking and as snuff. Tobacco contains the stimulant but poisonous alkaloid nicotine, which enters the bloodstream during smoking. The volatile tarry material also released during smoking contains carcinogenic chemicals (see carcinogen).

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to·bac·co (tə-bakґo) [L. tabacum] any of various plants of the genus Nicotiana, especially N. tabacum. 2. the dried and prepared leaves of N. tabacum; it contains various alkaloids, the principal one being nicotine, has qualities of both a sedative narcotic and an emetic and diuretic, and is also a heart depressant and antispasmodic. See also tobacco poisoning and nicotine poisoning, under poisoning.

Medical dictionary. 2011.

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  • Tobacco — To*bac co, n. [Sp. tabaco, fr. the Indian tabaco the tube or pipe in which the Indians or Caribbees smoked this plant. Some derive the word from Tabaco, a province of Yucatan, where it was said to be first found by the Spaniards; others from the… …   The Collaborative International Dictionary of English

  • tobacco — (n.) 1580s, from Sp. tabaco, in part from an Arawakan (probably Taino) language of the Caribbean, said to mean a roll of tobacco leaves (according to Las Casas, 1552) or a kind of pipe for smoking tobacco (according to Oviedo, 1535). Scholars of… …   Etymology dictionary

  • tobacco — [tə bak′ō] n. pl. tobaccos [Sp tabaco < ?; perhaps an old Sp name transferred to the New World plant] 1. any of a genus (Nicotiana) of chiefly tropical American plants of the nightshade family, with hairy, sticky foliage and long tubed, white …   English World dictionary

  • tobacco — см. Приложение 1 (Nicotaia tabacum). (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • tobacco — tobacco. См. табаки. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • tobacco — has the plural form tobaccos …   Modern English usage

  • tobacco — ► NOUN (pl. tobaccos) ▪ a preparation of the dried and fermented nicotine rich leaves of an American plant, used for smoking or chewing. ORIGIN Spanish tabaco …   English terms dictionary

  • Tobacco — For the plant genus, see Nicotiana. For the American electronic musician, see Tobacco (musician). Not to be confused with Tabacco. Part of a series on …   Wikipedia

  • tobacco — tobaccoless, adj. /teuh bak oh/, n., pl. tobaccos, tobaccoes. 1. any of several plants belonging to the genus Nicotiana, of the nightshade family, esp. one of those species, as N. tabacum, whose leaves are prepared for smoking or chewing or as… …   Universalium

  • tobacco — n. 1) to grow, raise tobacco 2) to cure tobacco 3) to chew tobacco 4) strong tobacco 5) chewing tobacco 6) a plug of (chewing) tobacco * * * [tə bækəʊ] raise tobacco a plug of (chewing) tobacco chewing tobacco strong tobacco …   Combinatory dictionary

  • Tobacco —    Indigenous to the Americas, tobacco is a sacred and powerful plant in many indigenous cultures. Its intoxicating effects were well known and rarely used for recreational purposes. In some cultures, it was never smoked or ingested in sufficient …   Historical dictionary of shamanism

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