Ego
Part of speech: noun
Definition: The self, especially with overtones of self-importance. The most conscious part of the mind, which mediates with one's surroundings.
Example sentence: I guess I have a little bit of an ego. I'm confidently cocky, you might say.
Self
Part of speech: noun
Definition: An individual person as the object of his own reflective consciousness.
Part of speech: adjective
Definition: same
Example sentence: The most satisfying thing in life is to have been able to give a large part of one's self to others.