Basilect

In linguistics, a basilect is a dialect of speech that has diverged so far from the standard language that in essence it has become a different language. A basilect represents the opposite end of the scale of linguistic formality from an acrolect.

Basilects typically differ from the standard language in pronunciation, vocabulary, and grammar, and can often develop into different languages, as the basilects of Vulgar Latin eventually developed into Romance languages.

Ebonics may be seen as a modern example of a basilect.