Le disque jaune - The amber light?

Question

I don't understand how the example "Le disque jaune" can mean "The amber light". Jaune=yellow, so I accept it can also mean amber. But how can disque mean light, doesn't it normally mean disc? This can however be a thing i haven't learned in English, as neither English nor French is my native language.

Tom Kelly · Answer

Hi Åb,I believe this terminology has its origins in French railway signaling. Originally the French system had a system of solid coloured disks, red, yellow etc. I guess when the signalisation evolved to use a system of couloured lights the "disque jaune" actually became a yellow light but the terminology was not updated to reflect this, so "yellow light"  = "disque jaune".This has nothing to do the traffic light system wher the yellow (amber) light is referred to as "feu jaune (orange)"I am no expert on railway signaling but I trust this expanation is accurate.Tom