solipsism

solipsism \SOL-ip-siz-uhm\, noun:

1. Philosophy. the theory that only the self exists, or can be proved to exist.
2. extreme preoccupation with and indulgence of one's feelings, desires, etc.; egoistic self-absorption.

A faint smile twitched the corners of O'Brien's mouth as he looked down at him. "I told you, Winston," he said, "that metaphysics is not your strong point. The word you are trying to think of is solipsism. But you are mistaken. This is not solipsism."
-- George Orwell, 1984, 1949

At quarter to four, his eyelids growing heavy as he read the two-page biography of Socrates, his eye was caught by another entry heading: "Solipsism." James had never realized solipsism was a philosophy. He had thought it was only an insult.
-- Sam Taylor, The Amnesiac, 2003

Solipsism entered English in the late 1800s from the Latin solus + ipse literally meaning "alone" + "self."