n. (pl. -os) 1 (in full tobacco-plant) any plant of the genus Nicotiana, of American origin, with narcotic leaves used for smoking, chewing, or snuff. 2 its leaves, esp. as prepared for smoking. tobacco mosaic virus a virus that causes mosaic disease in tobacco, much used in biochemical research. tobacco-pipe see PIPE n. 2. tobacco-stopper an instrument for pressing down the tobacco in a pipe.
[ Sp. tabaco, of Amer. ind. orig. ]