Definitions for "activist"
someone who does things to bring about political or social changes
an individual who is extensively and vigorously involved in political activity, either within or outside the governmental system
A person who intentionally acts to bring about civic, cultural, economic, political, or social change. This person’s actions support or oppose one side of a controversial argument. Activism may refer to a variety of actions, including protest, writing letters to newspapers or politicians, participating in rallies and street marches, and many other tactics to bring about change that promotes and protects human rights.
Keywords:  militant, reformer
a militant reformer
a person who works actively for a cause or movement back
a person in the Ubuntu community who has committed to observe the Ubuntu Code of Conduct
a person who gets up there in the frontlines and actually does the work
one who is aggressively active on behalf of a cause.
advocating a cause or engaged in activism