The Teleris Cluster was a stellar cluster. The inhabited planet Mundahla, a place famed for its star dancers, was located in this cluster.

Q offered to take Vash to this cluster and ultimately Mundahla in 2369, but she refused. (DS9: "Q-Less")

This cluster was only mentioned in dialogue.
According to the script, the pronunciation for Teleris was "TELL-her-iss". [1]