Terosa Prime was the prime planet in its star system.
Federation Professor Gideon Seyetik and his wife Nidell visited Terosa Prime in 2367, during which Nidell nearly died when she lost control of her psychoprojective telepathy and created an alter ego, Fenna. (DS9: "Second Sight")
This planet was only mentioned in dialogue.
According to the script, the pronunciation for Terosa was "tuh-ROW-suh".