What is "nalfeshnee"

In the Dungeons & Dragons fantasy roleplaying game, the nalfeshnee is one of the most powerful types of demon. In first edition Advanced Dungeons & Dragons, nalfeshnees were known as type IV demons. From second edition AD&D, the name "type IV demon" was revised to "nalfeshnee", taking the name of the greatest individual of their rank as the name for the entire breed.