Much like most of the bad guys in "Dragon Ball Z," the tagged-on letter to the show gained a new form, and fans had their own theories on what it could mean. One idea was that the "Z" stands for "Zenkai," which is not only Japanese for "last time" but also what Goku uses to describe a specific Saiyan trait that he and his race possess in the "Dragon Ball" manga, Chapter 283, "Ginyu Steps In."
For fans, Zenkai became another label for Saiyan Power, which is unique to the warrior race. In the heat of battle, Saiyans have the power to recover quicker than their opponents, even to the point of gaining greater strength to win whatever planet-shaking scrap they find themselves in. This feature makes Goku and the other Saiyan Z fighters the best line of defense. The greater beating they receive, the faster they heal, and the quicker they are to adapt should they be hit with the same attack in the future.
Additionally, the word also appeared in the show's closing theme for the song "Detekoi Tobikiri ZENKAI Power!" for the first 199 episodes of the show, only fortifying the reasoning behind the added Z. Whether fans choose to add more meaning to the letter or not, one thing can't be denied; "Dragon Ball Z" still sounds cool after all these years.
