how would you define selfish?

When people call someone bold and straightforward, does that imply that he or she is in fact selfish? Is someone who is easily tempered selfish deep deep inside? Is it because Hitler is selfish instead of merciless that millions of Jews were killed? 

If you think about it, you know I am also a selfish person. That is why I get irritated easily. But because I am a Christian, I know it is not holy, not Christ-like to be selfish; thus, I cry when I am frustrated with my temper, hoping it will wash away my shame. 
God, help me.