Ilidaria was an inhabited planet in the Ilidaria system in the Delta Quadrant. This planet was located less than three light years from a type-4 quantum singularity. Its inhabitants had sophisticated technology and were "quite friendly, most of time". (VOY: "Parallax")

This planet was only mentioned in dialogue.
According to the Star Trek Encyclopedia (4th ed., vol. 1, p. 356), this was the homeworld of the Ilidarians to which a trade mission was conducted later that season.
According to Star Trek: Star Charts (p. 83), this planet was visited by the USS Voyager on stardate 48734.