◙ conjunction 1. [formal] with the intention of preventing (something undesirable); to avoid the risk of • [正式] 免得，唯恐 »he spent whole days in his room, headphones on lest he disturb anyone. 他整天呆在屋里，头上戴着耳机，以免打扰别人。 (after a clause indicating fear) because of the possibility of something undesirable happening; in case • ［用在表示害怕的句后］怕，担心 »she sat up late worrying lest he be murdered on the way home. 她满心焦虑守候到很晚，怕他在回来的路上会被谋杀。
【语源】
1. Old English thȳ lǣs the 'whereby less that', later the læste
【用法】
1. There are very few contexts in English where the subjunctive mood is, strictly speaking, required: lest remains one of them. Thus the standard use is she was worrying lest he be attackednot lest he was …or she is using headphones lest she disturb anyonenot … lest she disturbs anyoneSee also subjunctive