The word **熄灯** (xī dēng) is a verb-object compound formed by combining the verb **熄** (xī), meaning "to extinguish" or "to put out," with the noun **灯** (dēng), meaning "lamp" or "light." Morphologically, it follows a common Chinese word-formation pattern where an action is directly paired with its object, creating a concise term meaning "to turn off the lights." The logic is straightforward and literal: the action of extinguishing (**熄**) is applied to the object, the light (**灯**), resulting in the specific meaning of switching lights off.