红灯 literally means 'red lamp' or 'red light', and in modern Chinese it most commonly refers to the red signal in traffic lights. The character 红 (hóng) means 'red', indicating color, while 灯 (dēng) means 'lamp' or 'light'. Together, they form a compound noun denoting the specific red light that signals vehicles and pedestrians to stop. This term is used exclusively in urban infrastructure contexts—not for decorative or household red lights.

In everyday speech, 红灯 carries strong functional and regulatory meaning: it’s not just a visual object but a command to halt. It appears frequently in driving instructions, public safety announcements, and news reports about traffic violations. Unlike English, where 'red light' can be used metaphorically (e.g., 'a red light district'), 红灯 in Chinese rarely takes figurative meanings—its usage stays tightly bound to traffic control systems and road safety.