idealism, the doctrine that a) truth, beauty and religious righteousness are more fundamental and useful than the external things in the world; b) things exist only as ideas in the mind rather than as material objects independent of the mind; c) things in the material world are actually manifestations of an independent realm of unchanging, immaterial models or forms.

an idealist - a) a person whose behaviour or thought is based on ideals; b) one who follows his ideals to the point of impracticality; a mere visionary or dreamer; c) an adherent or practitioner of idealism in art or philosophy.