Code Switching
Refers to the use of two (or more) codes (languages) in a single utterance, often without changing the topic of the utterance and within one sentence. A switch might occur on any level of a linguistic structure, and may effect for example, vocabulary, pronunciation, and grammatical structure.
Code switching is often thought of as a hallmark practice in multilingual communities worldwide. This practice was initially dismissed as random and deviant, and as a sure sign of linguistic deficiency in either language. However, it has since been recognized as a complex, skillful, strategic, and socially significant language practice, a tool for the speaker’s expression of identity, linguistic and cultural backgrounds.
Dialect
A form of language and its associated set of features that can be linked with a particular group based on a geographic region they occupy or social and economic status. A given language can have a number of dialects generally thought to be mutually intelligible, although this is not always the case. Dialects can vary in grammatical features, sounds, pronunciation, and also vocabulary.
Language
A shared system of communication, consisting of sounds, words governed by grammatical rules.
Language Contact
Language contact occurs when two or more languages or varieties interact. This contact might result in a high degree of bilingualism or multilingualism, it can also result in the rise of a new hybrid language variety, incorporating multiple languages, or it could also cause language shift and eventual loss of some languages and varieties.
Language Endangerment / Language Loss
A situation in which the very existence of a language is threatened as a result of declining use and a wide-spread break in intergenerational transmission between adults and children. This can happen in a variety of contexts, such as when an Indigenous community becomes a minority group governed and dominated by speakers of a different language, or following a group’s displacement from a territory.
See this link for more detailed information:
http://www.linguisticsociety.org/sites/default/files/Endangered_Languages.pdf
Language Ideologies
Language ideologies have been defined as “self-evident ideas and objectives a group holds concerning roles of language in the social experiences of members” (Heath 1989: 53). Especially in multilingual communities, language ideologies must be understood, and treated as socially, politically, and linguistically significant.
Language Reclamation
Involves efforts to restore and bring back into use a language that is referred to as sleeping, or deemed “extinct” or “dead” – one which no longer has fluent speakers. Not only does reclamation require the development of programs and activities to support language learners, it also involves language reconstruction from documentation materials, often requiring the assistance of linguistic experts.
Language Revitalization
Generally a term that refers to a variety of responses to the shift and decline in community’s language and its varieties of use. These responses include advocating and raising awareness of the shift or decline, and developing programs, activities, and materials to stop and reverse this process. It involves expanding the existing domains of language use while creating new ones in order to bring the language back into use in the community. See Fishman (1991) for steps towards reversing language shift.
Language Shift
A result of a language contact, when one language becomes gradually replaced by another. Speakers might first become bilingual, but gradually cease transmitting both language to children. This process can occur at different rates depending on the particulars of a situation, but often occurs over a longer period of time, as language transmission from one generation to the next diminishes.
Sleeping Languages
The term “sleeping languages” has been used for those languages that no longer have any speakers. The metaphor of “sleeping” has used to counter other, more gloomy metaphors such as “dead” and “extinct” language to provide for recognition that such languages can be brought back into use even if the have lost their fluent speakers.
An example of a sleeping language being awoken are the Miami reclamation efforts:
http://myaamiacenter.org/?page_id=301
UBC talk by Daryl Baldwin, Director of the Myaamia Center at Miami University (Ohio) titled “toopeeliyankwi, kati myaamiaataweeyankwi: We Succeed At Speaking The Myaamia Language” on reclaiming Myaamia, a formally sleeping language.