n. The habit of valuing everything only in reference to one's personal interest; pure selfishness or exclusive reference to self as an element of character.n. In ethics, the doing or seeking of that which affords pleasure or advantage to one's self, in distinction to that which affords pleasure or advantage to others: opposed to altruism. In this sense the term does not necessarily imply anything reprehensible, and is not synonymous with egotism.n. In metaphysics, the opinion that no matter exists and only one mind, that of the individual holding the opinion.