Altruism Part 2

What is the difference between being altruistic and being virtuous? Can one be altruistic without being virtuous, or virtuous without being altruistic? I found the diagram in class to be very helpful. I now understand altruism as a kind of sub-category to virtuosity. One can be virtuous without being altruistic, however, one cannot be altruistic without being virtuous. After our discussions in class, I feel a little better about understand altruism as a whole. What still eludes me, however, is the exact definition of 'virtue'. The nature of virtue, and what is truly virtuous, still confuses me. Is it that altruism is supposed to have an air of disinterestedness, and virtue is not? Is it that virtuosity is more about morality and goodness of the self, rather than almost carelessly looking out for others? I understand that their are many important differences between altruism and virtue, but I still don't understand what it means to be a virtuous human being. Is there one, over-arching, all-encompassing definition of 'virtue'? And how does a virtuous person get away without showing any kind of altruism?