How about breaking it down into components and analyzing the pieces?
What is
social?
3: of or relating to human
society, the interaction of the individual and the group, or the welfare of human beings as members of society
4a : tending to form cooperative and interdependent relationships with others
-ism
1: a distinctive doctrine, cause, or theory
The word
society seems to be an important ingredient.
Perhaps to an independent, paraplegic,
garbage-munching carnivore these ideas are foreign, but it would seem to me it is a
theory/doctrine of human welfare based on cooperative, interdependent relationships in society. But maybe this definition is too vague or broad?