ex·tra·ter·res·tri·al /-təˈrɛstriəl, ˈrɛs(h)ʧəl/
  (a.)地球外的
  extraterrestrial
       adj : originating or located or occurring outside Earth or its
             atmosphere; "is there extraterrestrial life?"
       n : a form of life assumed to exist outside the Earth or its
           atmosphere [syn: extraterrestrial being, alien]