idealistEnglishOxford New American Dictionaryidealist /īˈdē(ə)ləst, aɪˈdi(ə)ləst / ▸ noun 1 a person who is guided more by ideals than by practical considerations: he came to power with the reputation of a left-wing idealist. 2 Philosophy a person who believes in the theory of idealism: Hegel described himself as an absolute idealist.