Vain (adjective)

1. Having or showing an excessively high opinion of one's appearance, abilities, or worth.
2. Fruitless or unsuccessful.

Origin:

From the old french word "vain" which means "empty" and the latin word "vanus" which means "empty" or "useless".

Examples:

1. She is often vain and likes to look her best.
2. He is vain about his hair and spends a lot of time styling it.
3. The effort was in vain as the project was not successful.
4. The search was in vain as the missing person was not found.
5. The vain person is always looking for compliments.