吸烟 literally means 'to inhale smoke' and is the standard term for the act of smoking tobacco—most commonly cigarettes, but also cigars or pipes. The first character, 吸 (xī), means 'to inhale' or 'to suck in', while 烟 (yān) means 'smoke' or 'tobacco smoke'. Together, they form a verb that describes the physical action and its object as one inseparable concept. Unlike English, where 'smoke' can be both noun and verb, 吸烟 functions almost exclusively as a verb in modern usage and rarely appears as a noun without modification (e.g., 吸烟者 'smoker').

This word is widely used in public health campaigns, medical advice, and everyday conversation about habits and lifestyle choices. It carries a neutral-to-negative connotation depending on context: it’s factual in clinical settings ('He smokes') but often implies risk or disapproval in warnings ('Smoking is harmful'). While not slang, it’s more formal than colloquial alternatives like 抽烟 (chōu yān), especially in written materials and official discourse.