yeah . wikipedia is a credible source…
You could use any dictionary. It is usually a derogotary term, that much is clear, and that negative connotation is clearly related to undesirable behaviour (in the eyes of critics of such behaviour).
Collins dictionary:
usually derogatory
a person who campaigns zealously and vociferously for causes associated with social justice
The urban dictionary:
A person who uses the fight for civil rights as an excuse to be rude, condescending, and sometimes violent for the purpose of relieving their frustrations or validating their sense of unwarranted moral superiority. The behaviors of Social justice warriors usually have a negative impact on the civil rights movement, turning away potential allies and fueling the resurgence of bigoted groups that scoop up people who have been burned or turned off by social justice warriors.