- You may have been looking for the TOS episode, "The Empath".
Empathy is the ability to understand or feel the emotions of another being.
Some humanoids have extrasensory empathy. A Human-Betazoid hybrid is a known example of such empathy, as are the Lumerian, Napean, and presumably, Deltan people.
According to Berlinghoff Rasmussen, some of his closest friends were empaths. (TNG: "A Matter of Time")