In American English: "Reflex reflector"
In British English: "Retroreflector"
I like the French word better than either of those ("Catadioptre") because it has a cat.
Speaking of! Alors, let’s go racing in the snow and speaking French! It is daytime, so let’s stop in the middle of the race and replace a working Cibié headlamp with another working Cibié headlamp! Now let’s rev the engine, do a little heel-and-toe soft-shoe, and speak more French! Then at 5:50, let's pull in at the Chrysler dealer, speak some more French, and pay more attention to the Cibié headlamps!
Thanks a lot Dan for this old video clip by Chrysler France.
A good occasion to see in motion the "Chrysler" (how they were called here) Hemicudas... With their pilots Henri Chemin, Jean Claude Geral and Marie Laurent. They had to have a big heart to pilot these heavy cars on our narrow and winding roads :p