What is "archomental"

In the Dungeons & Dragons fantasy roleplaying game, archomentals are powerful exemplary beings of the Elemental Planes and rulers over the elementals. Although they are not truly rulers of their planes, archomentals like to consider themselves as such and often grant themselves regal titles like Prince or Princess. They are compared in the source material to the archfiends or celestial paragons, and are considered to be the elemental equivalent of such beings.