unthinkable
🇺🇸
/ʌnˈθɪŋkəbl/
🇬🇧
/ʌnˈθɪŋkəbl/
too shocking or impossible to imagine
The idea of failing the test was unthinkable to the hardworking student.
对于这位勤奋的学生来说,考试不及格的想法是不可思议的。