idealistic       
adjective uk/ˌaɪ.dɪəˈlɪs.tɪk/ us/ˌaɪ.diː.əˈlɪs.tɪk/
C1 理想主义的,空想的
believing that very good things can be achieved, often when this does not seem likely to other people
  When I was young and idealistic I believed it was possible to change the world. 我年轻时是个理想主义者,我相信改变世界是可能的。 
 She supports a number of idealistic causes. 她支持许多理想主义的事业。 
 See: idealist
 - More examples
- A lot of people think I'm idealistic and can't cope with the real world.
- Apathetic parents and long hours make even idealistic teachers give up.
- He's idealistic but might not be very practical.