Solipsism

The word of the day is solipsism:

In philosophy, the theory that only the self exists or can be proved to exist. Also an extreme preoccupation with and indulgence of one's feelings and desires. In other words, egoistic or self-absorption. Other forms include solipsismal, solipsist, and solipsistic.

Use it in a conversation today to impress all your friends.

(This is one of numerous words I had to look up while reading an exceedingly high-brow musicological text. One gets smarter just by LOOKING at this book)!