Selfish:Concerned with benefiting oneself.
The typical understanding of this word involves someone seeking to benefit themselves at the expense of others. It stems from a false philosophical belief that people's interest are normally opposed, and one man's benefit must be another's loss. In this view, if you are seek to benefit yourself, you must be willing to sacrifice others. In this framework, your choice is to sacrifice others, or sacrifice yourself. You're either "selfish", or selfless.
The problem is that in real life, actions that harm others are usually not in a person's actual self-interest. We benefit from having others in our lives as friends, loved-ones, teachers, or trading partners. Actions that destroy these relationships cannot be described as benefiting a person, even if they manage to get something in exchange.
Rational self-interest says that to really benefit your own life, you can't ignore or disregard the people in your life that you benefit from. To really benefit your life, your actions must take them into account.
The conventional view of selfishness rejects the possibility of rational self-interest. It implies that to pursue your own interest must be to disregard the interests of others. Properly, that view must be rejected and the definition should discard the false evaluation based on the faulty premise.