Kafir

Referring to Black Africans. Kafir is an Arabic word with meanings similar to Goy or Goyim of the Jews, only describing any non-Muslim person in a derogatory way. S. African Kaffir possibly imported during the Boer War by British soldiers who had fought in the Sudanese campaign. It just means those who are not in whatever religion the Arabic speaker adheres to (Christianity or Islam). It can be negative if someone uses a negative, derogatory tone of voice, but the word itself isn't "bad" used that way.