from
The Collaborative International Dictionary of English v.0.48
Immaterialism \Im`ma*te"ri*al*ism\, n. [Cf. F.
immat['e]rialisme.]
1. The doctrine that immaterial substances or spiritual being
exist, or are possible.
[1913 Webster]
2. (Philos.) The doctrine that external bodies may be reduced
to mind and ideas in a mind; any doctrine opposed to
materialism or phenomenalism, esp. a system that maintains
the immateriality of the soul; idealism; esp., Bishop
Berkeley's theory of idealism.
[1913 Webster]