I've seen some other people try and answer the question, and while their answers are all not bad, I think they miss the mark of what you're trying to ask.

The strict legal and rhetorical definition of justice is "giving each his or her due." This definition becomes problematic when one realizes that it is almost impossible to objectively determine what one is "due." Furthermore, it seems like in any situation the dues of one or many must be compromised for the dues of another one or many.

However, based on your comments on others' posts, it seems like you want a more broad moral definition of justice. Remember justice does not necessarily indicate anything moral. Legal justice is something entirely different. That said, a definition for moral justice is a lot harder to formulate. Because we don't even have a firm grasp on what amounts to good and what amounts to evil, or even what amounts to right or wrong. The world is a very complicated place and people have written endless amounts on what legal justice is, and untold more on what moral justice is.

If you want my personal opinion, moral justice is something that does not exist. Good and bad, right and wrong, are inextricably linked in every action and thereby reaction. Good can also come from bad and bad from good. The two have a fluid relationship. So to say that one can give just recompense is to say that good has been done to remedy bad. Even if we could ascertain whether a situation was mostly bad or mostly good, in order to judge that situation, we would have to know what events led up to the decision. We would have to know everything that caused the situation to occur and everything that caused those previous situations to occur. This effort to comprehend an infinite minutia is frivolous. Instead, we should move forward with a humble knowledge of our ignorance, and a mindfulness that we can only control our actions.