[countable] the result of a test or an exam when sb/sth is not successful
（考试）不及格 ●without ˈfail

1. when you tell sb to do sth without fail, you are telling them that they must do it
   务必；一定◆I want you here by two o'clock without fail.
   我要你两点钟之前务必来到这儿。