九界 (Jpn ku-kai or kyu-kai )
Nine of the Ten Worlds; those other than the world of Buddhas, or Buddhahood. The nine worlds are contrasted with the world of Buddhas to indicate the realm of delusion and impermanence. They are the worlds or realms of hell, hungry spirits, animals, asuras, human beings, heavenly beings, voice-hearers, cause-awakened ones, and bodhisattvas. In the Lotus Sutra, both the nine worlds and the world of Buddhas are viewed as different states or potential states of life rather than physical realms or locations. The nine worlds and the world of Buddhahood are mutually inclusive: the world of Buddhas, or the state of Buddhahood, is inherent within the nine worlds, and the nine worlds all exist within the state of Buddhahood. Thus, the sutra holds that all beings of the nine worlds possess the potential for Buddhahood, and that Buddhas are not without the nine worlds.
See also mutual possession of the Ten Worlds.