Language shift, also known as language transfer, language replacement or language assimilation, is the process whereby a speech community shifts to a different language, usually over an extended period of time. Often, languages that are perceived to be of higher-status stabilize or spread at the expense of other languages that are perceived—even by their own speakers—to have lower status. An example is the shift from Gaulish to Latin during the time of the Roman Empire.¹²³

Not to be confused with language change or code-switching.

Language assimilation may operate alongside other aspects of cultural assimilation when different cultures meet and merge.⁴⁵