The stuff coming off a fire is "el humo". To smoke a cigarette is "fumar". to smoke meat is "ahumar".
Fumas marijuana?
Él fuma su pipa.
Literally you can say.. ahora vengo, necisseto que fumo- ill be back, i need to smoke. Hope that helps :) not sure about my spelling on necisseto though :S
Going outside to smoke - que VA afuera a fumar.
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