/ veɪn; NAmE / adjective
1.
that does not produce the result you want
SYN useless :
She closed her eyes tightly in a vain attempt to hold back the tears.
I knocked loudly in the vain hope that someone might answer.
2.
( disapproving ) too proud of your own appearance, abilities or achievements
SYN conceited :
She's too vain to wear glasses.
—see also vanity
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IDIOMS
- in vain
—more at name noun
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WORD ORIGIN
Middle English (in the sense without real worth ): via Old French from Latin vanus empty, without substance.