fail² n without fail a) if you do something without fail, you always do it 必定，总是: Barry comes over every Friday without fail. 巴里每星期五必定会来。 b) used to tell someone firmly that they must do something 务必，一定〔用于告诫对方必须做某事〕: I want that work finished by tomorrow, without fail! 我要求那项工作必须在明天之前完成，不得有误！