What is Social Justice?

This seems like something that should have been addressed much earlier, but I'm curious how everyone defines social justice. These definitions frame our conversations and I want to know how others interpret the subject.

From Wikipedia: Social justice, sometimes called civil justice, refers to the concept of a society in which "justice" is achieved in every aspect of society, rather than merely the administration of law. It is generally thought of as a world which affords individuals and groups fair treatment and an impartial share of the benefits of society.

What does it mean when we say something is or isn't social justice? What subjects are included under the heading "social justice"?

I think this is particularly relevant when we're discussing topics that seem to fall outside the range of tradition social justice, such as wellness, suicide prevention, sustainability, etc. In some areas there is a clear connection, but these are disciplines that rarely collaborate. Are the goals of these groups fundamentally different or is this a failure to explore the interconnectedness of the issues? And if the groups are different, do we still have a responsibility to each other? I know we demand social justice mentality from all the groups on campus, but social justice groups often fail to reciprocate for wellness or sustainability.

I'd love to hear everyone's opinions!