Formal:
* Linguistic community: This is a technical term used in sociolinguistics to refer to a group of people who share a common language and language practices.
* Speech community: Similar to a linguistic community, this term emphasizes the shared norms and practices of language use within a group.
Informal:
* Language group: This is a broad term that simply indicates people who share a common language.
* Culture: This term refers to the shared customs, traditions, and values of a group of people. Language is often a key part of a culture.
* Nation: In many cases, a nation is defined by a shared language and culture. However, this is not always the case, as nations can be multi-lingual and multicultural.
* People: While less specific, this can be used in a general sense to refer to a group of people who share a common language.
Other possibilities:
* Ethnolinguistic group: This term emphasizes the connection between language and ethnicity.
* Linguistic family: This refers to a group of languages that share a common ancestor.
The best term to use will depend on the specific context. If you are writing a research paper, you would likely use more formal terms like "linguistic community" or "speech community." However, if you are talking about a group of friends who share a common language, you might simply use "language group" or "people."