a light1 FOR A CIGARETTE 用于香烟 SMOKEa match or something else to light a cigarette 火柴;打火机 Have you got a light, please? 请问你有火吗?
a light• Do you have a light?
→ a light at light1(3)
2 LITTLE/NOT VERYsomeone who does not smoke etc very much 抽烟/饮酒/食量等少的人 → a light smoker/drinker/eater etc at light2(2)