(thē′iz·əm) noun
1. Belief in, or in the existence of, God, a god, or gods: opposed to atheism.
2. Belief in a personal God as creator and supreme ruler of the universe, who transcends his creation but works in and through it in revealing himself to men. Compare DEISM, PANTHEISM.
3. Belief in one god; monotheism: opposed to polytheism.
4. Formerly, deism.
5. Philos. The doctrine that one supreme reality, intrinsically complete and perfect, is the final ground and source of everything other than itself: a doctrine resembling monotheism and some types of monism, but opposed to atheism, agnosticism, deism, materialism, pantheism, and polytheism. [<Gk. theos god]
—the′ist noun
—the·is′tic or ·ti·cal adjective
—the·is′ti·cal·ly adverb

(thē′iz·əm) noun Pathol.
The toxic effects of excessive tea–drinking. [<NL thea tea. See THEINE.]