n.1. a. Belief in direct experience of transcendent reality or God, especially by means of contemplation and asceticism instead of rational thought.
b. Such experience had by an individual.
2. Belief in the existence of realities beyond perceptual or intellectual apprehension that are directly accessible by subjective experience: belief in séances, astral projection, and similar mysticism.
3. Belief that is not based on evidence or subjected to criticism: "[When] grappling with the evils they have themselves exposed ... these lifelong Marxists drift off into vague mysticism and into worship of personality" (I.F. Stone).