吸烟(xī yān) - to smoke (a cigarette) in Mandarin

吸烟 (xīyān) is to smoke, built from 吸 (xī, to inhale, to breathe in) and 烟 (yān, smoke, also the word for cigarette). Put together, it is literally "to inhale smoke."

It is the standard word on every no-smoking sign: 禁止吸烟 (jìnzhǐ xīyān), "smoking prohibited." The related noun 烟 (yān) on its own covers both "smoke" and "cigarette," so 一支烟 (yì zhī yān) is "a cigarette."

The compound behaves like an ordinary verb-object pair: it takes 了 (le) for a completed instance, 吸烟了 (xīyān le), and can be split, as in 吸了一支烟 (xī le yì zhī yān, smoked a cigarette), even though 吸烟 (xīyān) is usually cited and used as a single unit.