Perfect

The Japanese term for the 5th stage of Digimon evolution is 完全体 (Kanzentai), which means "Perfect Body". (Dub: Ultimate).

Kanzentai Digimon are those that survived the toughest part of evolution and are now among the strongest Digimon. They evolve from the Adult form and sometimes (though very rarely) can evolve onto Kyuukyokutai ("Ultimate/Final Body") form.

(Note: In the English localization of Digimon, the "Perfect Body" level was referred to as Ultimate. Needless to say, this is a source for boundless confusion, because the most common translation for the post-Kanzentai evolutions is Ultimate.)

(Note also: "Perfect Body" is the official translation by Toei for Kanzentai however some fans have also translated it as "Complete Body" which is just as correct. However Kanzentai is in past tense where as Perfect and Complete are in present tense which does make both translations questionable.)

Baby I -> Baby II -> Child -> Adult -> Perfect -> Ultimate