kaffir vs kaffir corn

kaffir

noun
  • South African mining shares 

  • A member of the Nguni people of southern Africa, especially a Xhosa. 

  • A language spoken by the Nguni peoples of southern Africa, especially Xhosa. 

  • A black person. 

  • In Islamic contexts, a non-Muslim. 

kaffir corn

noun
  • The cultivated species of sorghum, Sorghum bicolor, used as a food for people and animals and in ethanol production. 

How often have the words kaffir and kaffir corn occurred in a corpus of books? (source: Google Ngram Viewer )