smokeless        
adjective uk/ˈsməʊk.ləs/ us/ˈsmoʊk.ləs/
 UK无烟的,不冒烟的 
not causing or allowing smoke
  If you live in a smokeless zone you have to use smokeless fuels instead of coal. 如果你生活在无烟区,你得使用无烟燃料,不能用煤炭。 
 smokeless tobaccoUS (可放在口中咀嚼的)无烟烟草
tobacco that is chewed or put in the mouth