The word you're looking for is "Satyagraha." It comes from a combination of the Sanskrit words "satya" (truth) and "agraha" (insistence). Gandhi's overall method was one of "Satyagraha" -- firmly but non-violently insisting on the truth and not backing down. Others who fought for civil rights, such as Martin Luther King, Jr., had great respect for Gandhi's "Satyagraha" approach and made use of similar methods to call attention to truth and achieve their aims as well.
