space cadet
US /ˈspeɪs ˌkæd.ət/
UK /ˈspeɪs ˌkæd.ət/

1.
怪人, 白日梦者, 心不在焉的人
a person who is out of touch with reality, often appearing dreamy, distracted, or eccentric
:
•
He's such a space cadet, always daydreaming during meetings.
他真是个怪人,开会时老是做白日梦。
•
Sometimes I feel like a space cadet when I forget simple things.
当我忘记简单的事情时,有时我觉得自己像个怪人。