What does RS mean on the Mitsubishi's Montero RS?

Don't quote me on this, but I believe it stands for Rally Sport; just like the RS in Chevrolet's Camaro RS. Although it is not widely circulated, this abbreviaton could be due in part to Mitsubishi's huge Rallying program in the 1980's and 90's. Mitsubishi placed quite a few Pajeros (aka the Montero in the U.S.) in the Dakar Rally and other Rally and Off-Road Races. Even today, the Pajero is still competing in the Dakar Rally and has clentched the Overall Win more than once. Hope that helped!