A traffic light, especially the red light that signals drivers to stop at an intersection.
A compound of 'stop' (from Proto-Germanic 'stuppa') and 'light' (from Old English 'lēoht'). The word is entirely American English, emerging in the early 1900s as traffic signals were invented. 'Stop' + 'light' literally describes what the device does.
Americans created the word 'stoplight,' but in Britain and most of the world, they say 'traffic light'—this is a perfect example of how English speakers in different countries invent different names for the same modern technology based on what part they think about most.
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