Language extinction

In linguistics, language death (also language extinction, linguistic extinction or linguicide, and rarely also glottophagy) occurs when a language loses its last native speaker. Language death is a process that affects speech communities where the level of linguistic competence that speakers possess of a given language variety is decreased, eventually resulting in no native or fluent speakers of the variety. Language death may affect any language idiom, including dialects and languages. Language death should not be confused with language attrition (also called language loss), which describes the loss of proficiency in a language at the individual level.

Language death is typically the final outcome of language shift, and may manifest itself in one of the following ways:

The most common process leading to language death is one in which a community of speakers of one language becomes bilingual with another language, and gradually shifts allegiance to the second language until they cease to use their original, heritage language. This is a process of assimilation which may be voluntary or may be forced upon a population. Speakers of some languages, particularly regional or minority languages, may decide to abandon them based on economic or utilitarian grounds, in favour of languages regarded as having greater utility or prestige. This process is gradual and can occur from either bottom-to-top or top-to-bottom.

Languages with a small, geographically isolated population of speakers can also die when their speakers are wiped out by genocide, disease, or natural disaster.

...
Wikipedia