smoking
n. uncountablen. the act of breathing in smoke from a cigarette, pipe, or cigar. Most people know it is bad for your health.
n. the inhalation and exhalation of the fumes of burning tobacco or similar substances. Often used to refer to the habit or the physical activity itself.
Smoking is not allowed inside the building.
Many countries have passed laws to ban smoking in public places like restaurants and parks.
Public health campaigns have successfully reduced the prevalence of smoking by highlighting the link between long-term tobacco use and various respiratory diseases.
From Middle English smokynge, smokiende, from Old English smociende (“smoking”), from Proto-Germanic *smukōndz (“emitting smoke, smoking”), equivalent to smoke + -ing.
From Middle English smokyng, smokynge, equivalent to smoke + -ing.
The noun is uncountable when referring to the activity or habit; it functions as a gerund derived from the verb 'smoke'.
I have a smoking habitI have a smoking habit / I smokeWhile 'smoking' is a noun, learners often use it where the verb 'smoke' is more natural for describing personal actions.