What is what does vain mean?

Vain refers to having an excessive or exaggerated sense of self-importance or being preoccupied with one's appearance or achievements. It can also refer to something that is fruitless or without result. For example, a person who constantly admires themselves in the mirror can be considered vain, or a project that is pursued without any hope of success can be considered a vain effort. In general, the term vain implies a sense of futility, arrogance, or self-centeredness.