vainer , vainest
A vain attempt or action is one that fails to achieve what was intended.
The drafting committee worked through the night in a vain attempt to finish on schedule.
起草委员会为按计划完成草案已通宵加班,但结果仍是徒劳。
If you describe a hope that something will happen as a vain hope, you mean that there is no chance of it happening.
He married his fourth wife, Susan, in the vain hope that she would improve his health.
他娶了第四个老婆苏珊,徒然地希望她能使他健康状况好转。
If you describe someone as vain, you are critical of their extreme pride in their own beauty, intelligence, or other good qualities.
He wasn't so vain as to think he was smarter than his boss.
他还没有自负到以为他比自己的上司还精明的地步。
in vain
If you do something in vain, you do not succeed in achieving what you intend.
He stopped at the door, waiting in vain for her to acknowledge his presence.
他停在门口,徒然地等着她跟自己打招呼。
If you say that something such as someone's death, suffering, or effort was in vain, you mean that it was useless because it did not achieve anything.
He wants the world to know his son did not die in vain.
他想让全世界都知道,他的儿子不是白白死去的。