idealism

Concise Oxford English Dictionary © 2008 Oxford University Press:
idealism/ʌɪˈdiːəlɪzəm/

▶noun

• 1 the practice of forming or pursuing ideals, especially unrealistically.

• 2 (in art or literature) the representation of things in ideal form.

• 3 Philosophy any of various systems of thought in which the objects of knowledge are held to be in some way dependent on the activity of mind.

– derivatives
idealist noun,
idealistic adjective,
idealistically adverb.