Medusan homeworld
The Medusan homeworld was an inhabited planet and the homeworld of the non-corporeal Medusans. 

In 2268, the  was assigned the mission of transporting Ambassador Kollos to his home. ()

Appendices

Background information 

A promotional Star Trek Explained video identified the Medusan homeworld as Visalayan.  Visalayan was first used as the indigenous name for the Medusan homeworld in The Worlds of the Federation (p. 60).

Apocrypha 
The Star Fleet Medical Reference Manual (p. 90) identified the Medusan homeworld as the fifth planet, Xi Hydrae V. The Worlds of the Federation (p. 60) identified the Medusan homeworld as class C, the fourth planet in the  system. 

FASAs The Federation sourcebook, described this world as the fifth planet in the Rhys system. The Star Trek: The Original Series - Core Game Book referred to the planet as Medusa III.

External links 
 
 

Unnamed planets
Homeworlds