- If you are vain you think about yourself a lot, specially how you look.
- She was so vain she spent hours looking at herself in the mirror.
- If something is vain, it means it was not successful.
- She made a vain attempt to feed the baby carrots, but he kept spitting them out into her face.
- If something is in vain, it means it happened for no reason or had no purpose.
- The Prime Minister said that the soldiers killed in the battle did not die in vain. They helped save many innocent people.