Nahmi IV was the inhabited fourth planet in its system.

In 2366, the Correllium fever broke out on the planet. As part of the research in finding a cure, the Mikulaks donated tissue samples. The USS Enterprise-D transported them. (TNG: "Hollow Pursuits")

This planet was only mentioned in dialogue.
"NAH-me" was the planet's pronunciation from the script pronunciation guide. [1]
According to Star Trek: Star Charts ("United Federation of Planets I"), in 2378, Nahmi IV was listed as a Federation member.