Any view saying that reality is in some way mental, or depends intrinsically - and not just causally - on mind (not necessarily the human mind).
The term may also apply to features of some philosophy, but is connected for philosophers with 'idea' rather than, as in popular usage, with 'ideal' in the sense of goal of behavior; nor does it apply now to Plato's theory of forms (or ideas) since though these are not material neither are they mind-dependent.
Idealism may be opposed to materialism or to realism. Sometimes the term 'idealism' refers to the opinion that reality can only be described from some point of view, not in a way that transcends all points of view.
Compare with: perspectivism
A C Ewing, ed., The Idealist Tradition (1957)