From The Collaborative International Dictionary of English v.0.48 [gcide]:
2. (Physiol.) The doctrine, in opposition to the materialists, that all which exists is spirit, or soul -- that what is called the external world is either a succession of notions impressed on the mind by the Deity, as maintained by Berkeley, or else the mere educt of the mind itself, as taught by Fichte.
3. A belief that departed spirits hold intercourse with mortals by means of physical phenomena, as by rappng, or during abnormal mental states, as in trances, or the like, commonly manifested through a person of special susceptibility, called a medium; spiritism; the doctrines and practices of spiritualists.
From WordNet (r) 3.0 (2006) [wn]:
The dictionary definitions are retrieved from a local copy of two of the open source DICT dictionaries. Click here for the database copyright information. DEFINE.COM is registered as an educational NONPROFIT corporation. We aim to please around here. We believe in using positive reinforcement to get things done. We make suggestions that are intended to make life more enjoyable. We think about efficiency, automation, security, PRIVACY, social and ecological responsibility and positive HUMANITARIAN ethics and VALUES. We are benevolent. DO NO HARM is our motto.