vain · adjective /veɪn/Full view
in vain
C1 without any success
Dictionary example:

I tried in vain to start a conversation.

Learner example:

We looked in vain for the guide through three London parks. (Certificate in Advanced English; C1; German)

a vain attempt/effort/hope
C2 A vain attempt/effort, etc. does not have the result you want.
Dictionary example:

I made a vain attempt to engage him in conversation.

Learner example:

Many flew to cities in the vain hope of earning money, thus increasing the number of the homeless . (Certificate of Proficiency in English; C2; French)

C2 too interested in your own appearance and thinking you are very attractive
Dictionary example:

He's terribly vain.

Learner example:

Men are vain creatures who worry, maybe exces[s]ively, about beauty and keeping up with standards of beauty set by society. (Certificate of Proficiency in English; C2; Spanish)

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