An apogee is the point in an orbit that was most distant from the object being orbited.
While in orbit about Nelvana III in 2366, Data picked up ionization disturbances that had been detected by a probe and indicated that they were on an orbital path with an eight hundred kilometer apogee. It turned out that they were created by a cloaked Romulan orbital probe. (TNG: "The Defector")
While being questioned in 2368, Nicholas Locarno told Rear Admiral Brand that Nova Squadron had "executed a low apogee turn around Titan." Jean Hajar confirmed Locarno's description, also confirming that the turn was two thousand kilometers closer to the moon than had been in their flight plan, but was still within safety parameters. (TNG: "The First Duty")