idealism

US /aɪˈdiː.ə.lɪ.zəm/
UK /aɪˈdiː.ə.lɪ.zəm/
1.

chủ nghĩa duy tâm

the belief that your ideals can be achieved, often when this does not seem likely to others:

:
She never lost her youthful idealism and campaigned for just causes all her life.