A star century was a unit of time. In 2269, following Kaz's attempt to kill Leonard McCoy for dancing with his woman, Xerius proposed that the IKS Klothos and its crew be frozen for a star century. James T. Kirk argued against the Romulan's suggestion, saying by punishing the Klingons, the Enterprise crew would suffer, too, as they needed the combined power of both ships to escape Elysia. (TAS: "The Time Trap")