vain

superl.

  1. Having no real substance, value, or importance; empty; void; worthless; unsatisfying.
  2. Destitute of forge or efficacy; effecting no purpose; fruitless; ineffectual; as, vain toil; a vain attempt.
  3. Proud of petty things, or of trifling attainments; having a high opinion of one's own accomplishments with slight reason; conceited; puffed up; inflated.
  4. Showy; ostentatious.

n.

  1. Vanity; emptiness; -- now used only in the phrase in vain.