also 'Rastus, masc. proper name, short for Erastus. As a stereotypical name of an American slave or derogatory for "black man," by 1881, perhaps from its use in the stories of Joel Chandler Harris.
African nation, by 1834, Ruanda, probably via French, named for indigenous people there, whose word for themselves is of unknown origin. The spelling with -w- seems to have predominated after c. 1970.
African nation, former French colony (Tchad), independent since 1960, named for Lake Chad, which is from a local word meaning "lake, large expanse of water." An ironic name for such a desert country. Related: Chadian.