Tshiluba is a member of the Bantu language family spoken by about six million people in the Democratic Republic of the Congo, where it is one of the national languages along with Lingála, Kiswahili and Kikongo. It is spoken mainly in Western and Eastern Kasai. Other names for the language include Cilubà, Luba, Luba-Kasai and Luba-Lulua.
The Tshiluba word, Ilunga, is apparently the world's most difficult word to translate. It means 'a person who is ready to forgive any abuse for the first time, to tolerate it a second time, but never a third time'.