I define self as EGO and here are some interesting quotes I've found:
"A false sense of separateness created by living within delusion."
"... limited sense of 'I' that is identified with the body, mind, and senses; sometimes described as 'the veil of suffering.'"
"The mistaken notion of "I", a separate self, from which all confusion and suffering arises."
"(Latin) The personal pronoun "I"; in philosophy and theosophy, the ego is the center of 'I-am-ship' or egoity in the human being. There are two such centers: the spiritual and impersonal, commonly called the individuality; and the personal, often called the soul or the personality. The former ego is unconditionally immortal, the latter ego is conditionally immortal, but in most cases mortal because of its lack of binding aspirations with its higher Over-self, the individuality."
All from ego&ie=UTF-8&oe=UTF-8" target="_blank">http://www.google.com/search?client=safari&rls=en-us&q=defin ego&ie=UTF-8&oe=UTF-8