Here is the meaning of the word, VAIN

Vain ( n. ) - Vanity; emptiness; -- now used only in the phrase in vain.
Vain ( superl. ) - Destitute of forge or efficacy; effecting no purpose; fruitless; ineffectual; as, vain toil; a vain attempt.
Vain ( superl. ) - Having no real substance, value, or importance; empty; void; worthless; unsatisfying.
Vain ( superl. ) - Proud of petty things, or of trifling attainments; having a high opinion of one's own accomplishments with slight reason; conceited; puffed up; inflated.
Vain ( superl. ) - Showy; ostentatious.