IDEALISM noun [ U ] uk/aɪˈdɪəlɪzəm/ us the belief that your ideals can be achieved, often when this does not seem likely to others идеализм idealist noun [ C ] a person who believes that it is possible to achieve your ideals идеалист idealistic adjective uk/aɪˌdɪəˈlɪstɪk/ us идеалистический