Antide was a star system, located somewhere in the space of the galaxy's Alpha or Beta Quadrants.
History and specifics[]
The Antide system's orbit was the location of a planetary system, including prime planet Antide Prime, homeworld of the Antidean civilization.
Antide Prime appeared on a star chart hologram that Data and Picard were studying in stellar cartography in the year 2371. (TNG movie: Generations)