Kaffir
Concise Oxford English Dictionary © 2008 Oxford University Press:
Kaffir /ˈkafə/
▶noun offensive, chiefly S. African an insulting and contemptuous term for a black African.
– origin from Arab. kāfir ‘infidel’, from kafara ‘not believe’.
usage: The word Kaffir was originally simply a descriptive term for a particular ethnic group. Now it is a racially abusive and offensive term, and in South Africa its use is actionable.
'Kaffir' also found in these Oxford entries:

