noun (n)

• (ethics) the theory that the pursuit of your own welfare in the basis of morality(noun.cognition)

  source: wordnet30
• concern for your own interests and welfare(noun.attribute)

  Synonym:
  egocentrism, self-centeredness, self-concern, self-interest
  Antonym:
  altruism, selflessness
  

  source: wordnet30
• The doctrine of certain extreme adherents or disciples of Descartes and Johann Gottlieb Fichte, which finds all the elements of knowledge in the ego and the relations which it implies or provides for.(noun)

  source: webster1913