Language Shift is when a group progressively abandons its language of origin, at the same time adopting the language of the socially or economically dominant group.
Language Death is noted from the language shifting, when the speakers leave their mother tongue and use other language, the mother tongue, slowly or quickly disappear.
Campbell (1994, p 1961) described the language death as “the loss of a language due to gradual shift to the dominant language in language contact situations”.