in vain 1. 徒劳 Their efforts were not in vain. 他们的努力没白费。 习惯用语as vain as a peacock1.象孔雀般地炫耀自己for vain1.徒劳地; 徒然in vain1.徒劳, 无益地2.轻慢地; 随便地