From Longman Dictionary of Contemporary Englishwhite supremacistˌwhite suˈpremacist noun [countable] SSRsomeone who believes that white people are better than people of other races —white supremacy noun [uncountable]
Examples from the Corpus
white supremacist• The killer: a white supremacist named Robert Chambliss.• They changed the subject by noting their prosecution of some highly publicized cases against the Klan and other white supremacist organizations.• There is growing evidence that white supremacist groups are renewing hate campaigns against Aborigines in some provincial towns. 