In military terms, a retreat was when a force willingly withdrew from a battle when there was little to no chance of victory.
During the reprisal of the Thal-Dalek battle, the invading Daleks forced the Thals to constantly retreat before the First Doctor reprogrammed the ionising towers to target the Daleks, the Dalek Supreme subsequently ordering a full withdrawal of all Dalek forces. (AUDIO: Return to Skaro)
When the War Doctor had seised Commander Partheus' TARDIS and ejected the Tear of Isha during the Battle for the Tantalus Eye, the Time Lord armada deployed to the Tantalus Eye retreated from the area. (PROSE: Engines of War)
Upon the opening of the Genesis Ark, the Cybusmen opted to retreat back to Pete's World, outmatched by the Daleks' superior technology. (TV: Doomsday)
During the Good Dalek Incident, Rusty transmitted a retreat signal to the command saucer, tricking the Daleks into thinking that the humans had activated the Aristotle's self-destruct. (TV: Into the Dalek)