Smoking has several meanings:

1. A chimney might be smoking after you light a fire. A barbecue grill smokes as meat cooks over hot coals. When something is smoking, visible wisps of gas and tiny particles rise into the air from whatever is burning or smoldering.
2. In casual speech, smoking can mean extremely fast or impressive: The pitcher threw a smoking fastball or That was a smoking guitar solo. The image suggests something so intense it practically burns.
3. The word also refers to the habit of breathing in smoke from cigarettes, cigars, or pipes. People once thought smoking tobacco was harmless or even sophisticated, but scientists discovered it causes serious diseases, including lung cancer and heart problems. Today, smoking is banned in many public places, and far fewer people do it than in the past.