A rentrillic trajectory was a type of navigational compensation for the random changes in physical constants inside chaotic space.
In 2375, when the USS Voyager became trapped in a region of chaotic space in the Delta Quadrant, a race of aliens who resided there attempted to communicate with Commander Chakotay, Voyager's first officer, by reactivating a gene causing him to experience a series of hallucinations. Through these visions, a means by which Voyager could safely return to normal space was communicated, although the geometry involved was not entirely understood by the crew. Despite this, Chakotay was managed to modify Voyager's deflector dish to induce a "paralateral rentrillic trajectory," by rerouting the sensor array through the dish, plotting a safe course back to normal space. (VOY: "The Fight")