Idiolect
An idiolect is defined as "the language use typical of an individual person." An individual's idiolect may be affected by contact with various regional or social dialects, professional registers, and in the case of multilinguals, various languages.
For scholars who view language from the perspective of linguistic competence, essentially the knowledge of language and grammar that exists in the mind of an individual language user, the idiolect is a way of referring to this specific knowledge. For scholars who regard language as a shared social practice, idiolect is more like a dialect with a speech community of one individual.
Read more about this topic: Variety (linguistics)