1 excessively proud or conceited, esp. about one's own attributes.
2 empty, trivial, unsubstantial (vain boasts; vain triumphs).
3 useless; followed by no good result (in the vain hope of dissuading them).
Phrases and idioms:
in vain without result or success (it was in vain that we protested). take a person's name in vain use it lightly or profanely.
Derivatives:
vainly adv. vainness n.
Etymology: ME f. OF f. L vanus empty, without substance
Useful english dictionary. 2012.